J Obstet Gynaecol Res. 2026 Nov;52(11):e70560. doi: 10.1111/jog.70560.

ABSTRACT

AIM: Nifedipine is widely used as a tocolytic agent for threatened preterm labor. However, its hemodynamic effects in normotensive pregnant women, particularly when administered as a controlled-release formulation, remain unclear. We evaluated changes in maternal hemodynamics and adverse effects after controlled-release nifedipine administration in normotensive pregnant women with threatened preterm labor.

METHODS: This retrospective observational study included normotensive women with singleton pregnancies who received controlled-release nifedipine as maintenance therapy for threatened preterm labor between 2018 and 2025. Maternal blood pressure, heart rate, respiratory rate, hypotension (systolic blood pressure < 90 mmHg or diastolic blood pressure < 60 mmHg), tachycardia (≥ 120 beats/min), and adverse maternal and fetal effects were evaluated before and after nifedipine administration.

RESULTS: Overall, 38 women were included in the final analyses. Systolic blood pressure significantly decreased from 110.2 ± 9.1 mmHg to 107.5 ± 10.2 mmHg after administration (mean change, -2.7 mmHg; 95% confidence interval, -4.5 to -0.8; p < 0.01). Diastolic blood pressure did not change significantly (-0.7 mmHg; -2.2 to 0.8 mmHg; p = 0.35). Heart rate significantly decreased from 95.3 ± 14.5 to 90.9 ± 12.4 beats/min. The incidence of hypotension and tachycardia did not differ significantly after nifedipine administration. No emergency deliveries were attributed to maternal hypotension. Headache was the most commonly reported adverse effect (28.9%).

CONCLUSIONS: Controlled-release nifedipine was associated with a small decrease in systolic blood pressure without serious maternal or fetal adverse events. With appropriate monitoring, controlled-release nifedipine may be a feasible option for maintenance or adjunctive tocolytic therapy in normotensive pregnant women.

PMID:43006657 | DOI:10.1111/jog.70560