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Table 1 Enrollment, pregnancy, and births by eligibility status at initial consent

From: Impact of preconception enrollment on birth enrollment and timing of exposure assessment in the initial vanguard cohort of the U.S. National Children’s Study

  High non-tryer High tryer Total preconception Pregnant Total
Number of women consented 231 198 429 970 1399
Proportion of women consented in study 16.5 % 14.2 % 30.6 % 69.3 % 100.0 %
Number of pregnancies 54 111 165 970 1135
Proportion of women conceiving 23.4 % 56.1 % 38.5 % 100.0 % 81.1 %
Proportion of pregnancies in study 4.8 % 9.8 % 14.5 % 85.5 % 100.0 %
Number of women giving birth 44 98 142 780 922
Proportion of pregnant women with known birth 81.5 % 88.3 % 86.1 % 80.4 % 81.2 %
Proportion of births in study 4.8 % 10.6 % 15.4 % 84.6 % 100.0 %
  1. Eligibility status at consent often differed from eligibility status at original screening because of a delay in implementing preconception enrollment. Of the 970 enrolled pregnant, 228 were not pregnant at initial screening. See Fig. 1 and reference #11