Antihypertensive drugs and foetal growth in hypertensive syndromes in pregnancy

Objective: To study the effects of several classes of antihypertensive drugs on foetal growth in pregnant women. Design: A retrospective analysis of a computerised database of 313 pregnancies of 225 women with hypertensive disorders (gestational hypertension, preeclampsia, chronic hypertension with or without superimposed preeclampsia) attending an antenatal hypertension clinic from 1980-1997 was performed. The classification of hypertension in pregnancy was based on the International Society for the Study of Hypertension in Pregnancy guidelines. The ponderal index (baby weight/length³ x 10⁴) was used as a measure of intrauterine growth retardation since it is independent of gestational age. The ponderal index values were logarithmically transformed for the statistical analysis. Results: The pregnancy outcomes according to the groups of no drugs, several monotherapies and multiple drugs were as follows: n Baby weight (gr) mean (SD) Baby length (cm) mean (SD) Log (ponderal index) (Kg/m³ x 10⁴) mean (SD) No drugs 87 3128 (795)* 50.7 (4.6)* 1.37 (0.06)* Atenolol 76 2427 (668)* 48.3 (3.8)* 1.34 (0.06)* Labetalol 22 2520 (861) 47.0 (5.5)* 1.36 (0.06) Ca blockers 12 2837 (859) 49.4 (5.0) 1.35 (0.05) Methyldopa 15 2796 (760) 48.3 (3.8) 1.40 (0.05) Multiple drugs 95 2209 (776)* 46.0 (5.1) 1.35 (0.06) *=p<0.05 ANOVA, 4 patients on diuretics, 1 patient on oxprenolol and 1 patient on ACE inhibitor were excluded from the analysis The significantly lower ponderal index value observed in the atenolol group remained so after accounting for other covariates like age, smoking status, race, being primi- or multigravida race, and classification of hypertensive disease in pregnancy (MANOVA p<0.0001). Further analysis showed that mere were no differences in the ponderal index among pregnant women who started atenolol (as monotherapy) in the first trimester (n=33, mean(SD)=1.34(0.06)), in the second trimester (n=14 mean(SD)=1.36(0.05)) or the third trimester (n=29 mean(SD)=1.33(0.07)). Conclusions: Atenolol given during hypertension in pregnancy is related to foetal growth retardation, and this effect is irrespective of the trimester that it is administered.