Pregnancy outcomes in familial hypercholesterolemia: a registry-based study

Women with familial hypercholesterolemia (FH) are prone to early cardiovascular disease and death. It is unknown whether FH adversely affects pregnant women and birth outcomes. We determined whether heterozygous FH women are at higher risk of premature birth (<37 gestational weeks), delivering children with low birth weight (<2500 g) and/or with congenital malformations compared to women in general.

We linked information from the Medical Genetics Laboratory with that of the Medical Birth Registry of Norway. We included 1869 FH women (≥ 14 years) from the Medical Genetics Laboratory and about 2 million (general population) from the Medical Birth Registry of Norway during the period 1967 to 2006. The registry match resulted in analysis of 2319 births of 1093 women with heterozygous FH. The mean (SD) prepregnancy total cholesterol concentration was 9.59 (2.06) mmol/L (370 [80 mg/dL]), whereas the concentration of total cholesterol was not available during pregnancy. The frequencies of prematurity, low birth weight, and congenital malformations for the 40-year period in the FH population were 6.8, 5.0, and 3.3, respectively. The corresponding values for the general population were 6.2, 5.2, and 3.2. The corresponding odds ratios were 1.11 (95 confidence interval 0.94-1.31; P=0.23), 0.96 (0.79-1.15; P=0.64), and 1.09 (0.87-1.37; P=0.45).

Women with FH do not appear to have a higher risk of preterm delivery or of having infants with low birth weight or congenital malformations than women in general, but, although this is unlikely, some undetected bias may obscure the real differences.