10: Maintenance nifedipine vs. placebo: A prospective, double blind trial

Article Outline

• Objective
• Study design
• Results
• Conclusion
• Copyright

Back to Article Outline

Objective 

To test whether treatment with nifedipine after arrested preterm labor prolongs pregnancy and improves neonatal outcomes.

Back to Article Outline

Study design 

A prospective, randomized, double-blind, multi-center study was conducted. After successful tocolysis of preterm labor patients were randomized to 20 mg nifedipine or an identical-appearing placebo every 4-6 hours, and treatment was continued until 37 weeks. The primary outcome was attainment of 37 weeks gestation. Patients were included between 24 and 34 weeks if they had 6 or fewer contractions per hour, intact membranes, and <4 cm cervical dilation. Exclusion criteria included placental abruption or previa, fetal anomaly incompatible with life, or maternal medical contraindication to tocolysis. In order to have an 80% power to detect a 50% reduction in birth prior to 37 weeks, with an alpha of .05 and a beta of .2, 66 patients were required. Statistical comparisons were made using 2-sided Fisher’s Exact tests, Student t-tests, and Mann-Whitney tests.

Back to Article Outline

Results 

71 patients were randomized, 2 were excluded after randomization, and 1 was lost to follow up. 35 patient received placebo and 33 received nifedipine. There were no maternal demographic differences between groups. Results are shown in the table.

Nifedipine vs. placebo outcomes

	Nifedipine	Placebo	p-value
Achieved 37 weeks	13 (39%)	13 (37%)	1.00
Delivery delay (days)	31	30	0.81
Mean GA delivery	35.0	35.2	0.82
Delivery delay >48 hours	33 (100%)	33 (94%)	0.49
>1 week	31 (94%)	31 (89%)	0.67
>2 weeks	28 (85%)	27 (77%)	0.54
>3 weeks	24 (73%)	24 (69%)	0.54
>4 weeks	22 (67)	19 (54%)	0.33
BW (grams)	2453	2531	0.69
Composite neonatal morbidity	10 (30%)	7 (20%)	0.41

Back to Article Outline

Conclusion 

Prolonged tocolysis following an episode of arrested preterm labor did not significantly prolong pregnancy or improve neonatal outcomes.