GENERAL TERMINOLOGY
Live birth is defined as presence of some signs of life after expulsion of baby, e.g. heart beats, cord pulsations, breaths or definite movements of voluntary muscles, irrespective of their duration or placental/cord separation.
Fetal death is defined as absence of such signs in expelled/extracted products of conception and may be divided into—(a) Earlyfetal deaths or abortions (lt;20 weeks or lt;500 gm or lt;25 cm); (b) Intermediate fetal deaths (20-28 weeks; 500-999 gm or 25-35 cm), and (c) late fetal deaths (gt;28 weeks, gt;1000 gm or gt;35 cm). Intermediate and late fetal deaths are also termed Stillbirths.
Intrauterine period spans from the day of conception to the day of delivery (40 weeks or 280 days ±2 weeks). Accordingly, a newborn may be classified as full term (3741 weeks), preterm (lt;37 weeks) or post-term (42 weeks). Babies born between 34-37 weeks are also termed as Late preterms, while those born before 28 week of gestation are considered as extreme preterms.
Intrauterine period includes two important phases in human life—embryonic period till first 8 weeks, predominantly characterized by organogenesis; and subsequent fetal period till birth, characterized by anatomical increase in body size and physiological maturation of various functions.
Neonatal period extends from birth to first 28 days of life and includes two important phases—early neonatal period from birth to 7th day and late neonatal period from 8th to 28th day.
Low birth weight: Since precise gestational assessment may be difficult in community practice, birth weight (BW) is often used as an indicator of neonatal maturity and health. A term newborn weighs ~3000 ±500 gm. Babies with BW of lt;2500 gm (up to 2499 gm) are termed low birth weight (LBW), while those weighing gt;3.5 kg are considered as large for date. Babies with BW of lt;1500 gm are also termed as very low birth weight (VLBW) and those lt;1000 gm as extreme low birth weight (ELBW).
Perinatal period: Late intrauterine period (gt;28 weeks or gt;1000 gm) and early intrauterine period (till 7th day) is considered as a continuum and together, termed ‘-perinatal period'.
However, with increasing survival of extreme preterms in recent years, this critical period has been expanded to include a new category, i.e. extended perinatal period, from 22 week of gestation (or gt;500 gm) to 7 days of postnatal life.
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