Estimating the Proportion of All Observed Birth Defects Occurring in Pregnancies Terminated by a Second-trimester Abortion

Prenatal termination of pregnancy may underestimate risks or cause bias in epidemiological studies of birth defects if such studies measure only defects diagnosed postnatally. We aimed to estimate the proportion of all fetuses with birth defects terminated in the second trimester of pregnancy-overall and for specific defects.The study comprised all pregnancies ending in a singleton birth, miscarriage, or termination of pregnancy for which health...