Joan T. Bihun1, Jackie S. Roessler1, & H. Hill Goldsmith1
Prenatal influences and complications can affect twins differently than singletons. The purpose of this presentation is to document the normative developmental course of twin pregnancies and deliveries, and to investigate the role complications might play in determining genetic and environmental influences on subsequent development. Medical records information was analyzed in some detail for 111 relatively healthy mothers (mean= 30.5 years; 95% received some prenatal care) and their twins (mean GA 36.5 weeks, mean weight was 2611 grams) participating in a larger longitudinal study. Extensive norms were collected and analyzed including aspects such as bed rest, blood pressure, preterm labor, types of delivery, and placentation. An obstetrics composite based on a number of pregnancy complications was not related to ratings of infant temperament at 3 months or maternal depression at 3 or 9 months postdelivery. However, specific components of this composite did relate to pregnancy outcomes and indices of later development. For instance, mothers on bedrest delivered, on average, 1.4 weeks sooner than those who were not on bedrest. However, mothers on bedrest were more likely to deliver both twins vaginally. Bedrest, especially when prescribed in the third trimester, tended to relate to greater maternal depression at 9 months postpartum. Multiparous mothers were more likely to rate their twins as more fearful, less likely to orient for longer periods of time, and tended to rate them as less likely to smile or laugh at 3 months postpartum than did primiparous mothers. Interestingly, there were no temperament differences at 3 months between pre- and full-term infants. The results reveal the importance of specific obstetrical complications rather than composites in predicting maternal and infant behavioral outcomes in relatively healthy samples. The data will be used to make more precise estimations of genetic and environmental influences on infant temperament, cognition, and mother-infant interaction.
Address: 1202 W. Johnson St, Madison, WI 53706; 608-265-6250; jtbihun@facstaff.wisc.edu
1Department of Psychology, University of Wisconsin, Madison, WI 53706