Measurement Of Gestational

To operationalize the current definition of prematurity, accurate measures of the duration of pregnancy (i.e., gestational age) are needed. Several methods are used to determine gestational age, but many are based on prenatal ultrasounds, which have provided a window onto the fetus and allowed observation of fetal growth and development (Goldstein et al., 1988; Neilson, 2000; Nyberg et al., 2004; Timor-Tritsch et al., 1988 ; Warren et al., 1989). Most often, prenatal ultrasounds determine pregnancy duration with early measures of fetal size, when there is little individual variation in fetal growth. Individual variations in fetal growth increase with the duration of the pregnancy and become quite prominent by the third trimester. It is ironic that gestational age, which reflects time (duration of pregnancy), is in fact often operationally determined by measures by fetal growth. A number of fetal growth curves have been generated and used to monitor fetal growth during pregnancy.

TABLE 2-1 Methods for Determining Gestational Age

Category

Timing

Measure

Type

Maternal

Prenatal

First to third trimesters

Last menstrual period

recall Maternal

Prenatal

First to third trimesters

Obstetric clinical estimate*

exam

Obsteric

Detection of gestational sac, Crown-Rump

ultrasound

First trimester

Length

Fetal Size

Obsteric

Biparietal Diameter, Femur Length, Abdomi-

ultrasound

Second to third trimester

nal & Chest Circumference Anthropometric Measurements: Birthweight,

Fetal Size

Postnatal

Birth (within first day)

Length, Head Circumference, Foot Length

Infant Size

Postnatal

Birth to 7 days Three to four days after

External Physical Characteristics

Infant exam

Postnatal

birth to 40 weeks' PMA

Neurological Assessment: Amiel-Tison Combination: Dubowitz, Ballard, New Ballard

Infant exam

Postnatal

Birth to 4 or 5 days

Score and others**

Disappearance of Pupillary Membrane (Ante-

Infant exam Infant eye

Postnatal

Any time after birth

rior Vascular Capsule of Lens)

exam

*Includes onset of pregnancy symptoms, fundal height, time when fetal heartbeat first detected, time of quickening (maternal detection of fetal movement).

** Other combinations have been proposed but are less well known and are used less frequently (See Allen, 2005a for references). The new Ballard Score is most accurate in infants with less than 26 weeks if performed before 12 h after birth (See Allen, 2005a for references).

NOTE: L/S = lecithin-to-sphingomyelin ratio; PG = phosphatidylglycerol = ; PMA = . SOURCE: Allen (2005a).

Reprinted with permission from Mental Retardation and Developmental Disabilities, Vol. 11, Page 23, © 2005 by Wiley-Liss, Inc.

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Pregnancy Diet Plan

Pregnancy Diet Plan

The first trimester is very important for the mother and the baby. For most women it is common to find out about their pregnancy after they have missed their menstrual cycle. Since, not all women note their menstrual cycle and dates of intercourse, it may cause slight confusion about the exact date of conception. That is why most women find out that they are pregnant only after one month of pregnancy.

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