Premature Cardiac Disease and Death After Preterm Preeclampsia in Women Whose Infant Was Small for Gestational Age—Reply

In Reply On behalf of my coauthors, I appreciate and agree with the points raised by Carbillon about the potential interpretation of our findings of premature cardiovascular disease (CVD) and death in relation to preeclampsia and the use of differing cutoff points to define a newborn as small for gestational age (SGA) or preterm birth.¹ It is true that we did not adjust for maternal body mass index (BMI, calculated as weight in kilograms divided by height in meters squared). To clarify, when we stated that “the association between preeclampsia and postpregnancy cardiovascular risk was partly due to prepregnancy risk factors,”¹ we were referring to a rigorous Norwegian study of women who had standardized measurements of blood pressure, serum lipid levels, and BMI before and after pregnancy.² However, it is unlikely that higher maternal BMI is a major mediator between our observed higher risk of CVD in women with combined preterm delivery and a newborn affected by severe SGA. In the Canadian Maternity Experiences Survey (MES)³ of women with a singleton livebirth, the population-attributable fraction for preterm birth was higher in women whose BMI was less than 18.5 (2.6%; 95% CI, 2.5-2.7) than in women whose BMI was 30 or greater (0.3%; 95% CI, 0.1-0.4). For the outcome of SGA lower than the 10th percentile, the corresponding population-attributable fractions in the MES were 5.3% (95% CI, 5.2-5.4) in women with underweight BMI and −1.6% (95% CI, −1.7 to −1.5) in women with obese BMI.³