There is irrefutable evidence that maternal weight gain during pregnancy inluences birthweight. Martin and coworkers (2009) studied this using birth certificate data for 2006. Approximately 60 percent of women gained 26 Ib or more during pregnancy, and maternal weight gain positively correlated with birthweight. Nloreover, women with the greatest risk14 percent-for delivering a newborn weighing <2500 g were those with weight gain < 16 lb. Nearly 20 percent of births to women with such low weight gains were preterm.
Meaningful studies of nutrition in human pregnancy are exceedingly diicult to design because experimental dietary deficiency is not ethical. In those instances in which severe nutritional deiciencies have been induced as a consequence of social, economic, or political disaster, coincidental events have oten created many variables, the efects of which are not amenable to quantiication. Some past experiences suggest, however, that in otherwise healthy women, a state of near starvation is required to establish clear diferences in pregnancy outcome.
During the severe European winter of 1944 to 1945, nutritional deprivation of known intensity prevailed in a wellcircumscribed area of The Netherlands occupied by the German military (Kyle, 2006). At the lowest point during this Dutch Hunger Winter, rations reached 450 kcal/d, with generalized rather than selective malnutrition. Smith (1947) analyzed the outcomes of pregnancies that were in progress during this 6-month famine. Median neonatal birthweights declined approximately 250 g and rose again ater food became available. This indicated that birthweight can be inluenced significantly by starvation during later pregnancy. he perinatal mortality rate, however, was not altered. Moreover, the incidence of fetal malformations or preeclampsia did not rise signiicantly. Parenthetically, weight loss in obese women during pregnancy is also associated with an increased risk for low-birthweight neonates (Cox Bauer, 2016).
Evidence of impaired brain development has been obtained in some animal fetuses whose mothers had been subjected to intense dietary deprivation. Subsequent intellectual development was studied by Stein and associates (1972) in young male adults whose mothers had been starved during pregnancy in the aforementioned Hunger Winter. The comprehensive study was made possible because all males at age 19 underwent compulsory examination for military service. It was concluded that severe dietary deprivation during pregnancy caused no detectable efects on subsequent mental performance.
Several studies of the long-term consequences to this cohort of children born to nutritionally deprived women have been performed and have been reviewed by Kyle and Pichard (2006).
Progeny deprived in mid to late pregnancy were lighter, shorter, and thinner at birth, and they had a higher incidences of sub sequent hypertension, reactive airway disease, dyslipidemia, diminished glucose tolerance, and coronary artery disease. Early pregnancy deprivation was associated with greater obesity rates in adult women but not men. Early starvation was also linked to higher rates of central nervous system anomalies, schizophre nia, and schizophrenia-spectrum personality disorders.
hese observations and others have led to the concept of etal programming by which adult morbidity and mortality are related to fetal health. Known widely as the Barker hypothesis, as promulgated by Barker and colleagues (1989), this concept is discussed in Chapter 44 (p. 848).