Nausea and vomiting, two common side effects of early pregnancy, rarely create significant health problems for a mother and her unborn infant. Some women, however, develop hyperemesis gravidarum, a pregnancy-induced condition of excessive vomiting and weight loss. If weight loss is prolonged, fetal growth may decline. In fact, any condition that causes weight loss during pregnancy --- including recent gastric bypass surgery, anorexia nervosa, poverty, smoking, drug abuse or emotional disorders --- has the potential to negatively affect fetal health.
Low Birth Weight
Infants born weighing less than 5.5 lbs. are considered low birth weight. This designation is given to infants regardless of prematurity; a baby born five weeks early, for example, is considered low birth weight regardless of early delivery. Low birth weight infants are at greater risk of illness, disability and death in comparison to normal weight infants.
Small for Gestational Age
An infant is considered small for gestational age, meaning small in relation to his true age in weeks, if he plots significantly below average on standardized growth charts at birth. Small for gestational age infants do not always "catch up" to normal weight and size over time and may remain smaller than average through adulthood. An evidence report issued by the Agency for Healthcare Research and Quality indicated that small for gestational age deliveries are strongly associated with inadequate maternal weight gain.
Intrauterine Growth Retardation
Intrauterine growth retardation is caused when some factor, such as inadequate calories and nutrition, interfere with fetal growth in the womb. Repeated ultrasounds can diagnosis intrauterine growth retardation. A fetus diagnosed with intrauterine growth retardation is likely to be born small for gestational age or at low birth weight.
Prematurity
Weight loss during pregnancy is one of many factors that may increase risk of prematurity. In comparison to full-term, 40-week gestation infants, infants born just three weeks early are at increased risk of lung problems, poor coordination, breast-feeding difficulties, jaundice and developmental delays.
Exposure to Ketones
Weight loss in pregnancy increases the risk of ketosis, a metabolic state in which the body breaks down fat for use as energy. Ketones, the byproducts of ketosis, circulate in a woman's bloodstream and pass to her fetus through the placenta. Exactly how ketones affect a fetus remains controversial, although many practitioners monitor pregnant woman for ketones due to concerns about fetal stress and potential effects on fetal brain development intelligence.
Predisposition to Chronic Disease
Inadequate weight gain in a woman's second and third trimester could predispose a fetus to lifelong chronic disease risks, according to groundbreaking research proposed in 1992 by Dr. David Barker of the University of Southampton School of Medicine. His "Fetal Origins of Disease Hypothesis" suggests that inadequate calories in the womb may permanently alter function of vital organs responsible for energy and metabolism. Although his hypothesis remains unproven, years of follow-up studies support the idea that fetal calorie deprivation may predispose an infant to chronic diseases like obesity, diabetes, hypertension and cardiovascular disease.
References
- Agency for Healthcare Research and Policy: Outcomes of Maternal Weight Gain Evidence Report
- Plus Size Pregnancy Index: The Ketone Controversy
- "Diabetologia"; Type 2 diabetes mellitus, hypertension and hyperlipidaemia (syndrome X): relation to reduced fetal growth; Barker DJ; January 1993
- "British Medical Journal"; The fetal origins hypothesis-10 years on; Erikson, JG; May 2005
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