The proposed research continues our controlled prospective study of maternal growth during adolescent pregnancy. During the current study (phase 1), the main obstacle hindering the demonstration of maternal growth was identified, a method to overcome this problem was found, and an association of maternal growth with lower levels of ferritin and zinc and decreased infant birthweight (in multiparous adolescents, age 12-15 at first pregnancy) was demonstrated. Research on maternal growth during pregnancy has the potential to have a substantial impact on infant mortality and maternal and infant health throughout the world. We therefore propose to confirm and extend our work from phase 1 using a sample of multiparous adolescents large enough to address many research questions raised about the influence of maternal growth on the hypothesized competition for nutrients between mother and fetus. During phase 2, we propose to select as index cases 400 multiparous teenagers (age <- 18 years), each matched to two comparison subjects of the same ethnic group which include: (1.) nulliparous controls of the same chronological age as the index cases; and (2.) mature multiparous controls (age <- 30 years), who were age 20 or more at first delivery.
The aims of phase 2 are to monitor and to describe maternal growth by knee height during pregnancy and the postpartum, to correlate maternal growth by knee height with growth of other body segments and changes in fat-free mass, and to assess the prognostic importance of maternal growth, inter-pregnancy interval, and other factors on circulating micronutrients and other indicators of maternal nutritional status (dietary intakes, body mass, skinfold thickness), and to assess the prognostic importance of growth by knee height and inter-pregnancy interval on birthweight and length of gestation in multiparous adolescents. Further, we propose to follow 500 teenagers studied during phase 1 or phase 2 into a subsequent pregnancy (phase 3) to confirm that differences in micronutrients and birthweight are due to declines from the prior pregnancy and not differences in their initial level. As part of phase 3, we will examine the mechanism of the competition for nutrients, including the association between continued maternal growth and increased resistance in the fetal and uteroplacental circulation (an indicator of decreased blood flow to the uterus and fetus) and decreased transfer of nutrients from mother to fetus.
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