Date Published: November 30, 2011
Publisher: SAGE-Hindawi Access to Research
Author(s): Ferenc Bánhidy, Abdallah Dakhlaoui, István Dudás, Andrew E. Czeizel.
Objective. To evaluate the rate of preterm birth and low birth weight in the newborns of pregnant women with early and late onset pre-eclampsia according to folic acid supplementation. Study design. Birth outcomes of newborns were evaluated in 1,017 (2.7%) pregnant women with medically recorded pre-eclampsia and 37,134 pregnant women without pre-eclampsia as reference in the Hungarian Case-Control Surveillance System of Congenital Abnormalities, 1980–1996, in addition these study groups were differentiated according to the supplementation of high dose of folic acid alone from early pregnancy. Results. Pregnant women with pre-eclampsia associated with a higher rate of preterm birth (10.2% versus 9.1%) and low birthweight (7.9% versus 5.6%). There was a lower risk of preterm birth (6.8%) of newborn infants born to pregnant women with early onset pre-eclampsia after folic acid supplementation from early pregnancy though the rate of low birthweight was not reduced significantly. There was no significant reduction in the rate of preterm birth and low birthweight in pregnant women with late onset pre-eclampsia after folic acid supplementation. Conclusion. The rate of preterm birth in pregnant women with early onset pre-eclampsia was reduced moderately by high doses of folic acid supplementation from early pregnancy.
Pre-eclampsia (PE) is frequent (2–8%) and severe complications of pregnancy, and this multisystem disorder of pregnancy is characterized by pregnancy-induced hypertension and new-onset proteinuria during the second half of pregnancy [1–3]. PE is a major contributor to maternal mortality if associates with eclampsia and HELLP syndrome [4, 5]. Furthermore, since delivery is the only cure of PE, there is a higher risk of preterm birth up to 15%  and intrauterine growth retardation  with an increase in infant mortality and morbidity.
The HCCSCA is based on the comparison of exposures studied during the pregnancy of mothers of cases with different congenital abnormalities and the mothers of controls without any defect matched to the cases. Cases with congenital abnormalities are selected from the Hungarian Congenital Abnormality Registry  for the HCCSCA. Control newborns were selected from the National Birth Registry of the Central Statistical Office for the HCCSCA. In general, two newborns were matched individually to each case according to sex, week of birth in the year when cases were born, and district of parents’ residence of cases.
The total number of births in Hungary was 2,146,574 during the study period, thus 38,151 controls represented 1.8% of all Hungarian births. Of these 38,151 newborns, 1,017 (2.7%) had mothers with medically recorded PE in the prenatal maternity logbook. Of these 1,017 pregnant women with PE, 45 (4.4%) had later eclampsia while HELLP was not recorded.
The primary aim of the study was to evaluate birth outcomes of pregnant women with early (“placental”) and late (“maternal”) PE. The risk of adverse birth outcomes cannot be differentiated according to early and late onset PE defined in our study, because the onset between sixth and eighth gestational months associated with a higher risk of preterm birth and low birth weight. The secondary aim of the study was to estimate the possible effect of folic acid for the risk of preterm birth and low birth weight of their newborns. On one hand, the high dose of folic acid used in early pregnancy reduced the rate of preterm birth but not modified significantly the higher rate of low birth weight, that is, intrauterine growth retardation in pregnant women with early PE. On the other hand, this preventive effect of folic acid was not observed in pregnant women with late PE; in fact, there was somewhat but not significantly higher rate of preterm birth and low birth weight in pregnant women with late PE after folic acid supplementation.