Assisted Reproductive Technology

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Tiffany Von Wald and Kim Thornton Introduction

Assisted reproductive technology (ART) is by definition any treatment or procedure that includes the handling of oocytes and sperm or embryos outside the body for the purpose of establishing a pregnancy. In vitro fertilization (IVF) is the most common ART procedure. The first IVF baby was conceived in 1978 (Louise Brown) in Lancashire, England. IVF has been used in the United States since 1981.

Definitions

In vitro fertilization (IVF): A process including controlled ovarian hyperstimulation, surgical removal (retrieval) of oocytes, fertilization in the laboratory, and transcervical transfer of embryos into the uterus.

Gamete intrafallopian transfer (GIFT): A procedure that involves removing oocytes from a woman's ovary, combining them with sperm, and using laparoscopy to assist in placing the unfertilized oocytes and sperm into the fallopian tubes.

Zygote intrafallopian transfer (ZIFT): A procedure that involves removing oocytes from a woman's ovary, fertilizing them in the laboratory with sperm, then placing the single-cell embryo (zygote) directly into the fallopian tube utilizing laparoscopy.

Tubal embryo transfer (TET): A procedure that involves removing oocytes from a woman's ovary and fertilizing them in the laboratory with sperm. The resultant embryo(s) are placed directly into the fallopian tube utilizing laparoscopy 2-3 days later.

Donor oocytes: Eggs that are removed from one woman's ovaries to be used by another for IVF. Indications often include premature ovarian failure, gonadal dys-genesis, recurrent IVF failure, natural menopause, and inheritable disorders.

Gestational surrogacy: Treatment by which the gametes of the intended parents (genetic parents) are used to produce embryos, which are subsequently transferred to a woman who agrees to act as a host or surrogate carrier of the pregnancy.

Microsurgical epididymal sperm aspiration (MESA): A technique whereby a small needle is used to extract fluid and relatively mature sperm directly from an epididymal tubule.

Testicular sperm extraction (TESE): A procedure for extracting sperm by removing a small sample of testicular tissue through an incision in the testes under local anesthesia.

Intracytoplasmic sperm injection (ICSI): A micromanipulation technique that involves injecting a sperm directly into an egg in order to facilitate fertilization.

Assisted hatching (AH): A technique in which the zona pellucida (outer shell of the egg) is chemically or mechanically thinned prior to embryo transfer in order to improve the likelihood of subsequent hatching and implantation of the embryo.

Preimplantation genetic diagnosis (PGD): A technique used during IVF to test embryos for genetic disorders (aneuploidy or structural chromosomal abnormalities), inheritable single gene disorders, or gender, prior to embryo transfer. The procedure can involve evaluating the chromosomal composition of the oocyte via the extruded polar body, removing one or two blastomeres from the cleavage stage embryo, or by biopsy of the trophoectoderm of the blastocyst stage.

Infertility History and Evaluation

An initial infertility evaluation is traditionally begun after one year of unprotected intercourse; however, an earlier evaluation may be indicated for increased maternal age, irregular menstrual cycles, previous pelvic inflammatory disease (PID) or pelvic surgery.

One of the most important aspects of evaluating infertility is obtaining a thorough history from both partners. When evaluating the female partner, it is important to include the items listed in Table 16.1. When evaluating the male partner, it is important to include the items listed in Table 16.2.

Every infertility evaluation should begin with a complete physical exam. When examining the female partner, it is important to document height and weight, as well as body mass index (BMI = weight in kilograms/height in meters squared). There is a clear association between weight and infertility as well as a correlation between the woman's weight and the amount of gonadotropins needed to stimulate the ovaries. It is important to check for thyroid enlargement, nodules, or tenderness, as well as identifying excessive acne or facial hair, which may be associated with increased androgen levels. Evidence of acanthosis nigricans often indicates

Table 16.1. Evaluation of female partner

Female:

General Category

Length of infertility Gravity and parity

Menstrual history

Family history Surgical history

Gynecologic history

Medication and allergy history Social history Review of systems

Specific Points

Coital frequency, previous treatment History of spontaneous pregnancy, specific pregnancy outcomes, complications, history of recurrent pregnancy loss

Length of cycles (normal 21-35 days), duration and type of flow (may indicate fibroids or oligovulation), menstrual cramps and breast tenderness (molimina-signs of ovulation), dyspareunia

Recurrent pregnancy loss, endometriosis, birth defects, premature ovarian failure

Tubal ligation, ovarian cysts, endometriosis, pelvic infections, appendectomy, D&C

STDs, PID, abnormal pap smears and subsequent treatment

Tobacco use, alcohol use, illicit drug use

Symptoms of thyroid disease, pelvic or abdominal pain, weight changes, hirsutism, galactorrhea

Table 16.2. Evaluation of male partner

Male:

General Category Specific Points

Length of infertility Coital frequency, previous fertility, previous infertility treatment

Childhood illnesses Mumps, testicular injuries, undescended testes and injuries

Family history Infertility history, inheritable disorders

Urologic surgery Vasectomy, herniorrhaphy

Past medical history Diabetes, multiple sclerosis, STDs, recent febrile illnesses

Environmental toxins Heat, pesticides, industrial toxins

Medication Sulfasalazine, cimetidine (gonadotoxic but reversible);

and allergy history antihypertensives, antipsychotics, antidepressants

(ejaculatory dysfunction); anabolic steroids (decreased spermatogenesis)

Social history Tobacco use (decreased motility), alcohol use, illicit drug use (marijuana- decreased sperm count) Review of systems Impotence, ejaculatory dysfunction insulin resistance, a common finding with polycystic ovarian syndrome (PCOS). Other important features to note are: a "buffalo hump" (Cushing's syndrome); short stature, webbed neck, and shield chest (Turner's syndrome). Finally, a complete pelvic examination is crucial during the initial visit and should include evaluation for Mullerian defects, pelvic or abdominal masses, or tenderness, cervical abnormalities, and nodularity in the cul-de-sac. One should consider performing a cervical culture as well due to the association of chlamydia cervicitis and PID.

During the examination of the male partner, one should first evaluate height, evidence of disproportionate limb length, secondary sexual characteristics, and gy-necomastia (Klinefelter's syndrome). The genitourinary examination should include location of the urethral meatus (hypospadias), palpating the testes for location and size, palpating bilateral vas deferens, and noting any varicocele.

The evaluation of the infertile couple often includes a panel of screening tests. This includes a cervical Pap smear, maternal blood type and Rh, antibody screening, rubella status, RPR (syphilis), varicella status, hepatitis B, and cystic fibrosis. Screening for sexually transmitted diseases is also recommended for patients at high risk, and would include hepatitis C, HIV 1 and 2, HTLV, CMV, chlamydia, and gonorrhea.

Once the initial screening tests are obtained, it is important to first document evidence of ovulation. This may be performed using basal body temperature charting (biphasic-—ovulatory), urinary LH surge detection kits, or serum progesterone levels (>5 ng/ml^ovulatory). An endometrial biopsy (showing secretory phase) may also be performed, but this has limited use due to the cost and invasive nature of the test. "Luteal phase defect" is a condition in which inadequate progesterone is produced by the corpus luteum as evidenced by endometrial histological dating. This is a controversial topic when used in the evaluation of the infertile couple, and recent

evidence suggests that an endometrial biopsy for histological dating does not differentiate fertile from infertile women, and thus, should not be used in the routine evaluation of infertility.

Routine laboratory tests for infertility include a prolactin level (normal <20 ng/ mL) and TSH (normal <5 mIU/mL but varies with individual laboratories). Occasionally, one will want to obtain labs for excess androgen states (PCOS), such as free or total testosterone, DHEA-S, and 17-OH progesterone. A fasting glucose/insulin ratio is obtained in women with PCOS to identify insulin resistance, and a 24-hour urinary cortisol may be needed to rule out Cushing's syndrome.

An important feature of the infertility evaluation includes ovarian reserve testing. This is often performed by obtaining a cycle day 3 (CD3) serum FSH level. In general, a CD3 FSH <10 mIU/mL is considered normal, where 10-15 mIU/ mL is considered the "gray zone" and a CD3 FSH >15 mIU/mL is considered abnormal with diminished ovarian reserve. A CD3 estradiol is also often obtained, and if elevated, may indicate a shortened follicular phase with decreased ovarian reserve. A clomiphene challenge test is another route to evaluate ovarian reserve. It is often used in older women (>35 years) or those with shortened menstrual cycles. To perform the test, a CD3 FSH is obtained. Then, clomiphene 100 mg is given orally on days 5-9. On CD10, a repeat FSH level is drawn. If either the CD3 or CD10 FSH level is elevated (>10 mIU/mL), the test is abnormal. There is some evidence that the sensitivity of the clomiphene challenge test is higher than a basal CD3 FSH level (26% vs. 8%), although both tests are routinely used. Lastly, an antral follicle count (AFC) may be obtained using transvaginal ultra-sonography to assess the number of primordial follicles during the early follicular phase. In general, an AFC count of <4 follicles is associated with a poor ovarian response.

Tubal patency and uterine cavity contour should be evaluated prior to beginning any infertility treatment. The most widely used test is the hysterosalpingogram (HSG). This is a radiological test performed as an outpatient procedure where dye is injected into the uterus through a small catheter and is imaged as it passes through the uterine cavity and fallopian tubes. It can display evidence of uterine fibroids, polyps, and synechiae (adhesions), as well as tubal patency. A sonohysterogram is an office procedure where saline is injected into the uterus under ultrasound guidance. Although it can detect uterine cavity abnormalities, it cannot show tubal patency. A hysteroscopy/laparoscopy may also be utilized to evaluate the uterine cavity and well as tubal patency through chromotubation, but this procedure is obviously much more invasive and requires general anesthesia.

Finally, a semen analysis is required to rule out a male infertility factor. If the first semen analysis is abnormal, it should be repeated. Although normal reference values can vary between laboratories, the World Health Organization recommends the following normal reference values (Table 16.3).

Indications for ART

As mentioned previously, IVF is the most common ART procedure performed. Although IVF was originally designed to treat tubal disease, it is now utilized as a treatment for many causes of infertility. In addition to tubal factor infertility, other indications include endometriosis, male factor infertility, ovulatory disorders, unexplained infertility, ovarian failure, and a history of inheritable disease.

Table 16.3. Semen analysis: WHO normal reference values

Volume 1.5-5.0 mL

Viscosity <3 (scale 0-4)

Sperm concentration >20 million/mL

Total sperm number >40 million/ejaculate

Percent motility >50%

Forward progression >2 (scale 0-4)

Normal morphology >14% normal

Round cells <5 million/mL

Sperm agglutination <2 (scale 0-3)

Tubal Disease

Tubal disease accounts for approximately 13.6% of indications for ART procedures in the US. Some patients with mild distal tubal obstruction may benefit from reconstructive surgery prior to proceeding with IVF. However, the pregnancy rates in general are lower than with IVF, and the risk of ectopic pregnancy is greater. IVF is the recommended treatment for women who remain infertile after one year following reconstructive surgery. For women with severe distal tubal disease, IVF is the primary treatment. There is substantial evidence that pregnancy rates are improved in women who have surgical removal of hydrosalpinges prior to undergoing IVF. In one meta-analysis of three randomized controlled trials, the odds of pregnancy (OR = 1.75, CI 1.07-2.86) and ofongoing pregnancy and live birth (OR = 2.13, CI 1.24-3.65) were increased with laparoscopic salpingectomy for hydrosalpinges prior to IVF. The mechanism of this effect is not well understood, but fluid from the hydrosalpinges is inflammatory and may have a toxic effect on the embryo or the endometrium.

Proximal or mid-tubal obstruction is also an indication for IVF. The most common reason for proximal obstruction is previous tubal sterilization. Microsurgical tubal reanastomosis can be effective in select candidates, although IVF may be a better choice for women who are poor surgical candidates and those who only desire one additional pregnancy.

Endometriosis

Endometriosis accounts for approximately 6.7% of indications for ART in the US. Mild, moderate, and severe endometriosis has been shown to decrease fertility rates in women undergoing both IUI and IVF Pregnancy rates in patients with endometriosis have been demonstrated to have an approximate 45% reduction in pregnancy rates with IVF. Women with moderate and severe disease have a worse prognosis than those with mild and minimal disease. The proposed mechanisms include distorted anatomy (adhesive disease), abnormalities with oocyte development, and diminished endome-trial receptivity. Although surgical management is an option for infertility treatment in women, IVF is often the treatment of choice in women who are older, those with other infertility diagnoses, or previous treatment failures.

Male Factor Infertility

Male factor infertility as a single reason accounts for approximately 18.8% of indications for ART in the US. Male factors can contribute to infertility in up to 35% of couples. The vast majority of sperm problems can be detected by a simple semen analysis. In men with mild semen abnormalities, intrauterine insemination with washed and concentrated sperm may be effective. In patients who fail to conceive after intrauterine inseminations with ovulation induction, the next step in treatment is IVF. IVF allows an assessment of whether fertilization occurs. In cases of no fertilization, intracytoplasmic sperm injection (ICSI) is then indicated. In men with severe abnormalities (references vary), poor fertilization is often expected. In this instance IVF is indicated as a first line therapy with the addition of ICSI. The indications for ICSI remain controversial but often include the following parameters:

• Total motile sperm count <1 million

• Previous IVF cycle with no or poor fertilization

• Epididymal or testicular spermatozoa

Because the manipulation with ICSI overrides potential natural protection to prevent fertilization by sperm with damaged DNA, there is the potential that children born after ICSI might be at increased risk for congenital birth defects and/or chromosomal abnormalities. However, most studies to date have failed to identify any increased incidence of major malformations above baseline in children born after ICSI.

Ovulatory Disorders

Chronic anovulation is a common cause of infertility and accounts for 6% of indications for ART procedures in the US. In most women with chronic anovula-tion, polycystic ovarian syndrome is the cause. Polycystic ovarian syndrome is a disorder characterized by hyperandrogenism and anovulation. Many women with polycystic ovarian syndrome are also very obese and may have insulin resistance. The majority of these patients will respond to conventional ovulation induction (clomiphene or gonadotropins). In women who are obese or insulin resistant, their response to ovulation induction may be enhanced with the use of insulin sensitizing agents such as metformin. When these treatment regimens fail, IVF is a reasonable and useful option. Although women with PCOS often obtain a larger number of oocytes during retrieval, there appears to be a lower fertilization rate, presumably due to the endogenous hormonal imbalance. Despite a reduced fertilization rate, IVF pregnancy rates in women with PCOS are comparable to ovulatory women. Women with PCOS who have high estradiol levels and a large number of preovulatory follicles are particularly at risk for the development of a syndrome called ovarian hyperstimulation syndrome (OHSS) because of their exaggerated response to gonadotropins. Women with a PCOS like response to gonadotropins are also at risk. Typical symptoms of OHSS include abdominal distension as a result of fluid shifts from the vascular space to body cavities, dehydration, nausea, and shortness of breath, weight gain, and pelvic pain. Depending on the severity, OHSS may be treated conservatively with fluid restriction or with paracentesis (removal of fluid from the abdominal cavity).

Unexplained Infertility

Although the exact prevalence of unexplained infertility is unknown due to differing diagnostic criteria, it ranges from 10-30%. In 2002, unexplained infertility accounted for 11.1% of indications for ART procedures in the US. The highest success rates for treatment are with IVF (28.5%). As one might expect, the success rates decrease in all forms of treatment as maternal age increases.

Diminished Ovarian Reserve

Diminished ovarian reserve is a common diagnosis in ART centers and accounts for approximately 6.7% of indications for ART in the US. Diminished ovarian reserve implies that the ability to produce eggs is reduced. Causes of diminished ovarian reserve may include surgery, congenital abnormalities and advancing maternal age. Many women with diminished ovarian reserve will be diagnosed by ovarian reserve testing or after a previous stimulation cycle demonstrates production of low numbers of oocytes.

Other Indications for ART

Women who have a family history of an inheritable disease may be candidates for IVF with preimplantation genetic diagnosis (PGD). PGD is most often utilized in this scenario when there is a single-gene disorder, sex-linked disorder, autosomal recessive disorder, or balanced translocation. PGD is also utilized in some women with recurrent pregnancy loss, but the data are not clear regarding improved outcomes. To perform PGD one or two cells are removed from the embryo. These cells may then be analyzed for the presence or absence of a single gene order or for the presence of the correct number of chromosomes. This will enable couples to preconceptually evaluate embryos so that they can preferentially transfer those embryos that are not affected with a genetic disease or that have a normal chromosomal number. PGD is occasionally used for sex selection and family balancing, but this is highly controversial.

Donor oocytes are indicated when a woman has premature ovarian failure, has undergone natural menopause or if a woman has demonstrated poor oocyte recovery and embryo quality with her own eggs. The latter indication is most often seen in women of advanced maternal age.

Women who have Mullerian anomalies (congenital absence of the uterus and vagina) are often candidates for gestational carriers (surrogates). Likewise, women with severe uterine abnormalities (fibroids, adhesions) or a previous hysterectomy may also be candidates for gestational surrogacy. Because the success rates for IVF are so high, other techniques such as GIFT and ZIFT are rarely used. Occasionally, GIFT is performed for religious preferences. MESA and TESE are clearly performed for severe male factor infertility and oligo- or azoospermia. Assisted hatching is controversial and is used to potentially improve implantation rates. It is most frequently utilized in couples with recurrent failed cycles or prolonged in vitro culture, when a thickened zona pellucida is suspected.

Success Rates

Success rates for IVF centers are difficult to quantify because they are site-specific and depend on numerous factors. These include but are not limited to: patient characteristics, degree of ovarian stimulation, embryo culture quality, number of

Table 16.4. IVF pregnancy success rates based on maternal age, 2003

Maternal Age (in years) Live Births/Cycle

embryos transferred, and transfer technique. In general, success rates are reported using the following terminology:

• Pregnancy rate: definition varies from a positive serum or urine phCG to live birth

• Clinical pregnancy rate: the percent of patients with at least one gesta-tional sac in the uterine cavity with fetal cardiac activity

• Live birth rate: percentage of patients with a live birth from an ART cycle

• Implantation rate: the number of clinical pregnancies divided by the number of embryos transferred

The Centers of Disease Control and Prevention (CDC) reports the most recent ART success rates from reporting centers in the US. In 2003, the total number of ART cycles reported was 112,872 while the number of live babies born as a result of ART cycles was 35,785. Of all the ART procedures performed, 74% were fresh, nondonor egg cycles. Of all the cycles cancelled, 82.9% were due to inadequate egg production. The rate of spontaneous abortion increases dramatically as the maternal age increases. The overall live birth rate per retrieval for different ART procedures using fresh, nondonor eggs was as follows:

• IVF without ICSI (intracytoplasmic sperm injection), 33.4%

• Combination of IVF with or without ICSI and either GIFT or ZIFT, 28.3% It is important to remember the success rates vary depending on the factors listed above, in addition to patient diagnosis. For example, in 2003 the highest live birth rate for fresh, nondonor cycles was in the ovulatory dysfunction infertility group (33.9%), while the lowest success rate was in the group with diminished ovarian reserve [14.3%]. The success rates also vary dramatically based on maternal age (Table 16.4).

Complications

Multiple Gestation

By far the greatest risk of IVF today is multiple gestations. Multiple gestations ultimately depend on the number of embryos transferred; thus the risk is primarily iatrogenic. In women under the age of 35 years, twin pregnancy rates can be as high as 40% when two high quality embryos are transferred. In general, ART increases the risk of multiple pregnancies by 10-fold above baseline (35% vs. 3% in the general

population). It is true that the success rates in IVF improve with a greater number of embryos transferred, but only to a certain point. Beyond this point, only the risk of multiple pregnancy increases. Another risk factor for multiple pregnancy is maternal age. Younger women tend to be at higher risk of multiple pregnancy when more than one embryo is replaced. The problem with multiple gestations lies in the risks during pregnancy to both the fetuses and the mother. A greater risk of preterm delivery is the most significant consequence of multiple gestation. Multiples also have a higher risk of congenital malformations, and monochorionic twins are at increased risk of twin-twin transfusion syndrome. This can cause significant morbidity or even mortality for one or both fetuses. There also appears to be an increased risk of cerebral palsy in multiple pregnancies compared to singletons. Lastly, there appears to be a slightly higher risk of monozygotic twinning following ART compared to the general population. The mechanism of this is not well understood but is believed to be due to trauma to the zona pellucida with herniation of the blastocyst.

Parents with multiple gestations, especially high-order multiples (three or more), frequently must face the decision of multifetal pregnancy reduction. This can be emotionally traumatic for couples that have struggled with the inability to become pregnant for long periods and the psychological morbidity is well documented.

There are obstetrical risks for the mother associated with a multiple pregnancy as well. Women carrying multiple gestations, especially higher order gestations, are at increased risk of hypertension, preeclampsia, and preterm labor. They are more frequently treated with prolonged bed rest and operative delivery compared to women carrying singleton pregnancies.

Ovarian Hyperstimulation Syndrome (OHSS)

OHSS can occur when a woman over-responds to high-dose gonadotropin stimulation. Risk increases with larger numbers of developing follicles and greater number of eggs retrieved. Younger women also tend to be at higher risk of OHSS compared to older women. Pregnancy will also increase the risk of OHSS as well as the severity and duration of it. Although the pathogenesis is not well defined, OHSS appears to be dependent on hCG as well as angiogenic factors. Most women who present with OHSS show signs of increasing abdominal distention, ascites, nausea, vomiting, decreased urine output, hypercoagulability, and electrolyte imbalance. If symptoms are severe, there is also an increased risk of deep venous thrombosis. OHSS can be classified as mild, moderate, or severe; however it is uncommon to see severe OHSS requiring hospitalization. Most of the time, women with OHSS can be treated symp-tomatically with expectant management. Occasionally, women will need to undergo a paracentesis to remove excess abdominal fluid (often done transvaginally under ultrasound guidance). This procedure frequently results in immediate improvement in patient discomfort and symptoms.

Ectopic Pregnancy

Pregnancies implanted outside the uterus are much more common in ART-conceived cycles than the general population (5% vs. 1-2%). The risk is higher in women with tubal disease or a prior history of ectopic pregnancy. The mechanism is not well understood but is likely due to natural migration of the embryo into the tube after transfer or inadvertent direct tubal embryo transfer. The risk of heterotopic pregnancy in the general population is very rare (1 in

10,000), but the risk is increased substantially in women who conceive after IVF or ovulation induction.

Other Risks

There is a small risk of internal bleeding, vascular injury, and infection from oocyte retrievals. Bleeding from the vaginal wall is fairly common after oocyte retrieval and usually stops spontaneously after the procedure or with the application of pressure. Severe pelvic infection is rare (<1%), and prophylactic antibiotics are usually not needed unless the patient is at high risk for pelvic inflammatory disease.

Fetal Risks

There are currently a number of studies suggesting an increased risk of birth defects in babies conceived after IVF. In cases where IVF and ICSI has been performed for a severe male factor, a several-fold increase was found in spontaneous anomalies of the sex and autosomal chromosomes and an increased risk of inherited chromosomal defects. Another study has suggested an increased incidence, albeit small, of Beckwith-Wiedemann and Angelman syndromes, which are complex disorders of growth and development associated with aberrant imprinting at chromosome 11q15.5 and the UBEA3 gene locus on chromosome 15q11-13, respectively. These disorders are the result of genetic alterations affecting the regulatory mechanism of genes, rather than DNA sequence (imprinting). Finally, there is some evidence to indicate that the risk of birth defects (heart, muscle or skeletal) is slightly higher in babies conceived through IVF as compared to babies conceived naturally. What remains to be determined is whether it is the IVF procedure itself or whether the increased risk is due to the infertility population undergoing treatment. Certainly ongoing research is required to better investigate the true fetal risks associated with ART outcome. Appropriate counseling of couples regarding the potential for risk associated with ART is recommenced.

Key Points

1 The infertility work-up involves a thorough evaluation of both male and female partner.

2. Indications for ART include male factor infertility, unexplained infertility, ovulatory disorders and ovarian failure.

3. Advanced ART procedures include PGD, oocyte donation and gestational surrogacy.

4. Interpretation of success rates must consider the IVF center, patient characteristics, stimulation protocols, number and quality of embryos transferred and transfer techniques.

5. Complications with ART are rare but include bleeding, infection, ovarian hyperstimulation and multiple pregnancy.

Suggested Reading

1. Steptoe PC, Edwards RG. Birth after the preimplantation of a human embryo. Lancet 1978; ii:366.

2. Wickland M, Enk L, Hamberger L. Transvesical and transvaginal approaches for the aspiration of follicles by use of ultrasound. Ann N Y Acad Sci 1985; 442:184.

3. Palermo G, Jorid H, Devroey P et al. Pregnancies after intracytoplasmic injection of single spermatozoon into an oocyte. Lancet 1992; 340:17.

Van Steirteghem AC, Liu J, Joris H et al. Higher success rate by intracytoplasmic sperm injection than by subzonal insemination Report of a second series of 300 consecutive treatment cycles. Hum Reprod 1993; 8:1005.

Handyside AH, Kontogianni EH, Hardy K et al. Pregnancies from biopsied human preimplantation embryos sexed by Y-specific DNA amplification. Nature 1990; 3:768. Green BB, Weiss NS, Daling JR. Risk of ovulatory infertility in relation to body weight. Fertil Steril 1988; 50(5):721-6.

Chong AP, Rafael RW, Forte CC. Influence of weight in the induction of ovulation with human menopausal gonadotropin and human chorionic gonadotropin. Fertil Steril 1986; 46(4):599-603.

Westrom L, Wolner-Hanssen P. Pathogenesis of pelvic inflammatory disease. Genitourin Med 1993; 69(1):9-17.

Gardner D et al. Textbook of assisted reproductive techniques. 2nd ed. London: Taylor and Francis, 2004.

Speroff L, Fritz M. Clinical gynecologic endocrinology and infertility. 7th ed. Philadelphia: Lippincott Williams and Wilkins, 2005.

Coutifaris C et al. Histological dating of timed endometrial biopsy tissue is not related to fertility status. Fertil Steril 2004; 82(5):1264-72.

Barnhart K, Osheroff J. Follicle stimulating hormone as a predictor of fertility. Curr Opin Obstet Gynecol 1988; 10(3):227-32.

Hendricks DJ et al. Antral follicle count in the prediction of poor ovarian response and pregnancy after in vitro fertilization: A meta-analysis and comparison with basal follicle-stimulating hormone level. Fertil Steril 2005; 83(2):291-301. World Health Organization. Laboratory manual for the examination of human semen and sperm-cervical mucus interaction. 4th ed. Cambridge University Press, 1999. Johnson NP, Mak W, Sowter MC. Laparoscopic salpingectomy for women with hyd-rosalpinges enhances the success of VF: A Cochrane review. Hum Repro 2002; 17(3):543-8.

Adapted from the Centers for Disease Control and Prevention (CDC). 2003 ART Success Rates (www.cdc.gov/reproductivehealth/art.htm).

Barnhart K, Dunsmoor-Su R, Coutifaris C. Effect of endometriosis on in vitro fertilization. Fertil Steril 2002; 77(6):1148-55.

DeBaun MR, Niemitz EL, Feinberg AP. Association of in vitro fertilization with Beckwith-Wiedemann syndrome and epigenetic alterations of LIT1 and H19. Am J Hum Genet 2003; 72:156-160, [CrossRef] [ISI] [Medline].

Maher ER, Brueton LA, Bowdin SC et al. Beckwith-Wiedemann syndrome and assisted reproduction technology (ART). J Med Genet 2003; 40:62-64. Olson CK, Keppler-Noreuil KM, Romitti PA et al. In vitro fertilization is associated with an increase in major birth defects. Fertil Steril 2005; 84(5):1308-45.

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