Nifedipine-associated maternal oxygen desaturation in an IVF twin pregnancy complicated by preterm premature rupture of membranes: a case report.

OBJECTIVE

To report a case of nifedipine-associated maternal oxygen desaturation in an IVF-conceived twin pregnancy complicated by PPROM with complete clinical documentation, and to provide denominator context from a retrospective review of institutional experience prompted by this case.

STUDY

DESIGN

Case report at a single tertiary center. Following the Index Case, we conducted a retrospective review of all 103 patients who received nifedipine tocolysis at our institution over the preceding 2 years (January 2024-January 2026). Among these, 10 (9.7%) had IVF-conceived multiple gestations complicated by PPROM-the clinical profile shared with the Index Case; 3 of these 10 (30%) had developed oxygen desaturation. Only the Index Case had complete clinical workup and is reported in detail.

RESULTS

Among 103 nifedipine tocolysis patients, 10 (9.7%) had IVF-conceived multiple gestations complicated by PPROM; 3 of these 10 (30%) developed oxygen desaturation. Two additional cases lacked complete workup and could not be attributed to nifedipine. The Index Case: a 36-year-old with IVF-conceived DCDA twins at 23+3 weeks developed SpO₂ 88% to 90% within hours of nifedipine. Echocardiography: preserved LVEF; BNP 626 pg/mL; troponin I<0.01 ng/mL; chest radiography: no alveolar pulmonary edema. Magnesium sulfate was never concurrent with nifedipine; it was given once for fetal neuroprotection after Episode 1, before either rechallenge. SpO₂ normalized without diuretics after each nifedipine discontinuation. Two deliberate rechallenges (Episodes 2 and 3, both without MgSO₄) both reproduced desaturation; Episode 2 required intensive care unit admission. Atosiban was initiated without recurrence.

CONCLUSION

This case, strengthened by two positive rechallenges occurring without concurrent magnesium sulfate, provides compelling temporal evidence for nifedipine-associated respiratory compromise in an IVF twin pregnancy with PPROM. The pattern of desaturation without radiographic alveolar pulmonary edema, elevated BNP, and resolution without diuresis suggests subclinical hemodynamic perturbation as the underlying mechanism. Clinicians should maintain heightened vigilance for unexplained oxygen desaturation during nifedipine tocolysis in this patient population.