Head, Health Services Research and Pharmacoepidemiology Unit FISABIO Valencia, Spain
Background: There is lack of consensus regarding the safety of antihypertensive drugs (AH) during pregnancy and the independent role of chronic hypertension (CH). Most existing evidence has important limitations.
Objectives: To assess the safety of intrauterine exposure to AH, and the role of CH on pregnancy outcomes, in an attempt to disentangle the effect of the medications from that of the illness itself, by considering hypertension control (i.e measurements of blood pressure).
Methods:
Design: Retrospective population-based cohort of all pregnant women and their offspring (N=600,000), 2009-2020. The hypertension subcohort will be comprised of women with a diagnosis of chronic hypertension (CH) before the conception date or until week 20 of pregnancy. Cohorts will be followed from 3 months pre-conception until death, loss of coverage or end of pregnancy. The Valencia Health System Integrated Database was used.
Setting: Valencia region, specifically, the population covered by public health system (97%; 5 million inhabitants).
Exposures: 1) women with CH exposed to AH during pregnancy, (2) women with CH non-exposed to AH during pregnancy (controlled and uncontrolled), (3) women without CH unexposed to AH during pregnancy.
Main outcome measures: Low birth weight, preterm birth, congenital anomalies, abortion or fetal death and neonatal death. Congenital anomalies will be retrieved from the congenital anomalies’ registry, which includes population-based Information on live births, fetal deaths and terminations of pregnancy after prenatal diagnosis of a fetal anomaly. Some outcomes measures have not been included in the present preliminary analysis.
Statistical analysis: Characterization of the different cohorts. For this preliminary analysis exposure to AH are described by trimester of pregnancy. Type of end of pregnancy are estimated for the different exposure groups. IPTW analysis is foreseen to assess the adjusted risks for the different exposure groups by trimester and therapeutic class.
Results: We retrieved 180632 pregnancies (preliminary sample), from which 5083 (2.8%) had a diagnosis of CH. Differences between women with and without CH were observed in virtually all types of pregnancy end, being the most remarkable, the rates of termination of pregnancy (9.6% vs 4.7%). From the hypertensive women, 33% were treated. From them, 1290 (25%) were exposed to AH in the 1st trimester, 972 (19%) in the 2nd and 995 (20%), in the 3rd. Rates of pregnancy ends were similar between treated and untreated women with CH, except for spontaneous abortion (8.6% vs 13.6%).
Conclusions: Preliminary data show differences for relevant pregnancy outcomes among exposure groups. Final analysis will provide key lacking evidence.
