Background:
Hypertension is associated with poorer outcomes in pregnancy. There is conflicting evidence regarding the pregnancy effects of tighter blood pressure control in the first trimester. Our study aimed to investigate associations between tight blood pressure (BP) control and pregnancy outcomes in women with chronic hypertension and pre-gestational diabetes mellitus (PGDM).
Method
A retrospective audit of data from pregnant women with PGDM from 2 centres in South-Western Sydney from January 2005 to June 2020 was conducted. Data were obtained from a district wide electronic database and hospital medical records. Women with a history of chronic hypertension were identified from this cohort. Pregnancy outcomes examined were preeclampsia, preterm delivery (<37 weeks) and birthweight percentile in women with tight BP control (≤135/85mmHg) compared to those with less tight BP control in the first trimester (>135/85mmHg).
Results
There were 494 women in the cohort and 46 had a history of pre-pregnancy chronic hypertension. Tight Bp control in the first trimester was seen in 30(65.2%) women . There were no significant differences between tight and less tight BP groups in age, number of IVF pregnancies, smoking, pre-pregnancy ACE/ARB, calcium, and aspirin use. However, women with less tight BP control had a significantly higher body mass index(BMI). There was no significant difference between the groups in birth weight percentile (Mean:50(28)vs 46(27),p=0.69), preeclampsia (26.7% vs 12.5%,p=0.24) or preterm delivery (72% vs 77%,p=0.54). On multivariate analysis there was still no association between tight BP control and preterm delivery, preeclampsia rate and birthweight percentile after controlling for age, aspirin, calcium use and comorbidities.
Conclusion. In our study, first trimester tight BP control in women with PGDM and chronic hypertension was not associated with a change in birthweight percentile, or preterm delivery. A larger prospective study would help determine the effect of first trimester BP control on pregnancy outcomes.