Recurrent Preterm Labor Research Articles

Vaginal versus Intramuscular Progesterone in the Prevention of Recurrent Preterm Labour

Background: Preterm labHarbor is characterized as the occurrence of uterine contractions of sufficient frequency and intensity to affect the cervix's progressive effacement and dilation before to term gestation. Objective: Comparison of vaginal and intramuscular progesterone to prevent premature labor in women with a history of spontaneous preterm labor recurrence. Patients and Methods: From April to November 2020, Al-Hussein Hospital, Al-Azhar University, conducted a comparative clinical trial study. In this research, one hundred (100) of pregnant women have been selected and divided into 3 groups (vaginal progesterone group (A), intramuscular progesterone group (B) and control group (C)) with a history of prior spontaneous premature labor. Results: Statistically significant differences were found among the progesterone groups and the control group with respect to NICU admissions, with a higher percentage of NICU admission among the control group (63.3%) compared to the progesterone groups (25.2%). There were also statistically significant differences among the vaginal progesterone group & the intramuscular progesterone group as regards NICU admission with higher percentage of NICU admission among the intramuscular progesterone group (40%) compared to the vaginal progesterone group (11.4%). Conclusion: In ladies who have had repeated spontaneous preterm labors, progesterone used prophylactically decreases the rate of premature labor, lowers the frequency of uterine contractions, and enhances the symptoms of preterm labor. In women at risk for PTL, vaginally administered progesterone was almost as effective as intramuscular progesterone in preventing PTL, with the vaginal route having a superior impact.

9 Low dose aspirin for the prevention of recurrent preterm labor (APRIL): a randomized controlled trial

To evaluate the effectiveness of aspirin compared to placebo for the prevention of preterm birth (PTB) when initiated in early pregnancy in women with a previous spontaneous preterm birth (SPTB). We performed a multicenter, double-blind, randomized controlled trial (APRIL, NTR 5675). We recruited women with a singleton pregnancy and a history of SPTB (singleton pregnancy 22+0 - 37+0 weeks) following either preterm prelabor rupture of membranes or spontaneous contractions. After informed consent, participants were randomly assigned to daily aspirin (80 mg) or placebo started between 8+0 and 16+0 weeks gestation. Treatment was continued until 36+0 weeks gestation or delivery. Primary outcome was PTB before 37+0 weeks gestation. Secondary outcomes included a composite of poor neonatal outcome (bronchopulmonary dysplasia, periventricular leukomalacia >grade 1, intraventricular hemorrhage >grade 2, necrotizing enterocolitis >stage 1, retinopathy of prematurity, culture proven sepsis or perinatal death). A sample of 384 women was required to detect a PTB reduction from 36 to 23% (α-error 0.05, β-error 0.2). Analyses were performed by intention to treat. Between May 2016 and June 2019, we randomly allocated 194 women to aspirin and 193 to placebo. The PTB rate was 21.2% in the aspirin group versus 25.4% in the placebo group (RR 0.83; 95% CI 0.58-1.2). SPTB occurred in 20.1% versus 23.8% of women (RR 0.84; 95% CI 0.58-1.2). For women who were ≥80% compliant with study medication, PTB rates were 18.5% versus 24.8% (RR 0.75; 95% CI 0.46-1.2). The poor neonatal outcome rate was 4.6% versus 2.6% (RR 1.79; 95% CI 0.61 to 5.3). There were no significant differences in maternal morbidities such as hypertensive disorders and postpartum hemorrhage. Our data did not demonstrate a reduction of PTB in women with a previous SPTB who used aspirin 80 mg. The RR for PTB is comparable to larger studies on aspirin in other groups of women. A small reduction of PTB from aspirin in women with a previous SPTB cannot be excluded with the current sample size.

Oral dydrogesterone as an adjunctive therapy in the management of preterm labor: a randomized, double blinded, placebo\u2010controlled trial

BackgroundPreterm birth is a major challenge in obstetric and perinatal care. It is the leading cause of neonatal death. The primary aim of this study was to evaluate the efficacy of oral dydrogesterone on latency period in managing preterm labor. The secondary aims were to evaluate the gestational age at delivery, percentage of preterm delivery before 34 weeks and 37 weeks, time to recurrent uterine contraction, pregnancy outcomes, neonatal outcomes, compliance and side effects.MethodsThis was a randomized, double blinded, placebo-controlled trial. Forty-eight pregnant women with preterm labor, singleton pregnancy, and gestational age of 24–34 weeks were enrolled into the study. The study group received 10 mg of oral dydrogesterone three times per day and the control group received placebo. All pregnant women received standard treatment with tocolytic and antenatal corticosteroids.ResultsThe median latency periods were not significantly different between the dydrogesterone group (27.5 days) and placebo group (34 days, p = 0.45). Additionally, there were no differences in the gestational age at delivery, percentage of preterm delivery before 34 weeks and 37 weeks, pregnancy outcomes, neonatal outcomes, compliance and side effects. However, the time to the recurrence of uterine contractions in participants that had recurrent preterm labor was longer in the dydrogesterone group than in the placebo group (30.6 ± 12.3 vs 13.7 ± 5.0 days, p = 0.01).ConclusionsAdjunctive treatment with 30 mg of oral dydrogesterone could not prolong latency period in preterm labor when compared to placebo.Trial registrationClinicalTrials.gov (Clinical trials registration: NCT 03935152, registered on May 2,2019).

COMPARATIVE STUDY BETWEEN CALCIUM CHANNEL BLOCKER AND PROGESTERONE THERAPY IN PREVENTION OF RECURRENT PRETERM LABOR

Background: Preterm labor (PTL) is the leading cause of perinatal and neonatal morbidity and mortality and strongly related to the developmental and neurological disabilities later in life. Objective: To compare between calcium channel blocker and progesterone in the prevention of Preterm Labor in patients with history of recurrent spontaneous preterm labor. Patients and Methods: A comparative clinical study was done at Al-Hussein Hospital on one hundred pregnant women with history of previous spontaneous preterm labors were selected in this study, and randomly arranged into two groups: calcium channel blocker group (A), and progesterone group (B). Results: There was no statistically significant difference between all groups as regards age, parity and number of previous preterm labors, There was a statistically significant difference between the progesterone group and the calcium group as regards GA at delivery, with higher percentage of lower GA at delivery among the progesterone group (35.61 weeks) compared to the calcium group (37.11 weeks), There was a statistically significant difference between the progesterone group and the calcium group as regards mean values of birth weight with higher percentage of lower birth weight among the progesterone group (2.37 kg) compared to the calcium group (2.93 kg), There was a statistically significant difference between the progesterone group and the calcium group as regards mean values of five minutes APGAR Score with higher percentage of lower five minutes APGAR Score among the progesterone group (7.66) compared to the calcium group (8.57), There was no statistically significant difference between all groups as regards the mode of delivery. There was a statistically significant difference between the progesterone group and the calcium group as regards NICU admission with higher percentage of NICU admission among the progesterone group (40%) compared to the calcium group (17.1%), There was a statistically significant difference in different studied groups before and after progesterone administration as regards mean values of serum progesterone, There was a statistically significant difference in different studied groups before and after progesterone administration as regards mean values of serum calcium. Conclusion: The use of calcium channel blocker and progesterone reduced the rate of preterm labor, prolonged gestational age at delivery, reduced the frequency of uterine contractions, and improved the symptoms of preterm labor in women with history of recurrent spontaneous preterm labors. Calcium channel blocker was more superior on progesterone as regards prevention of recurrent preterm labor.

Didelphys uterus with recurrent preterm labour: case report

ENWEndNote BIBJabRef, Mendeley RISPapers, Reference Manager, RefWorks, Zotero AMA Abdelazim I, AbuFaza M. Didelphys uterus with recurrent preterm labour: case report. Journal of Obstetrics and Gynecological Investigations. 2020;3(1):35-36. doi:10.5114/jogi.2020.102419. APA Abdelazim, I., & AbuFaza, M. (2020). Didelphys uterus with recurrent preterm labour: case report. Journal of Obstetrics and Gynecological Investigations, 3(1), 35-36. https://doi.org/10.5114/jogi.2020.102419 Chicago Abdelazim, Ibrahim, and Mohannad AbuFaza. 2020. "Didelphys uterus with recurrent preterm labour: case report". Journal of Obstetrics and Gynecological Investigations 3 (1): 35-36. doi:10.5114/jogi.2020.102419. Harvard Abdelazim, I., and AbuFaza, M. (2020). Didelphys uterus with recurrent preterm labour: case report. Journal of Obstetrics and Gynecological Investigations, 3(1), pp.35-36. https://doi.org/10.5114/jogi.2020.102419 MLA Abdelazim, Ibrahim et al. "Didelphys uterus with recurrent preterm labour: case report." Journal of Obstetrics and Gynecological Investigations, vol. 3, no. 1, 2020, pp. 35-36. doi:10.5114/jogi.2020.102419. Vancouver Abdelazim I, AbuFaza M. Didelphys uterus with recurrent preterm labour: case report. Journal of Obstetrics and Gynecological Investigations. 2020;3(1):35-36. doi:10.5114/jogi.2020.102419.

BEE HONEY, ROYAL JELLY AND PROPOLIS FOR THE PREVENTION OF PRETERM LABOR

Abstract Background: In-vitro work showed that bee honey (BH) and royal jelly (RJ) had improvement on the mechanical performance of fetal membranes. Propolisis is known for its anti-infection properties. Consequently, we tested the possible prophylactic effect of these products against preterm labor (PL). Methods: Fifty-nine gravidas with history of recurrent PL were quasi-randomly assigned into 2 groups: group I (30 women) received daily ingestion of 20 ml of cotton-trifolium BH, 400 mg propolis and 2 grams of RJ from the 15th gestation week until the onset of labor or completion of 38 weeks' gestation; group II (29 women) served as controls. Primary outcomes assessed were: 1) incidence of PL, and, 2) gestation age at birth. Secondary outcomes were: 1) ultrasonic evidence of cervical changes of threatening PL, and, 2) total leukocyte count and C-reactive protein. Results: Twenty-two pregnancies of group I went to term as compared to 13 of controls (75.9 %, 44.8%; P< 0.01). Average gestation weeks at birth were 36.3 and 31.1 (P<0.01 %). Cervical ultrasonographic signs of PL threat were elicited in 11 and 19 cases of groups I and II respectively (36.7, 65.5%; P<0.01). High leukocyte counts and C-reactive protein were found in 10 and 15 women of cases and controls respectively (33.3, 51.7%; P < 0.05). Conclusion: Bee honey, royal jelly and propolis may be effective for reducing the risk of PL. Further studies are required to elucidate the possible mechanisms and the best application route.

Study of the Relationship between Anti-Peroxidase Antibody and Miscarriage, Preterm Labor and IUGR in Egyptian Pregnant Women

Background: This research studied the relationship between anti-peroxidase anti-body in euthyroid pregnant female and miscarriage, preterm labor and IUGR in Egyptian patients. Patients and Methods: This prospective study was carried on patients who attended to the Obstetrics and Gynecology department of Tanta University Hospital for routine antenatal care from January 2016 to November 2016. 80 women enrolled in the study and were divided into four groups, 20 cases for each group, a control group, recurrent unexplained abortion group, preterm labor group and IUGR group. A Thyroperoxidase (TPO) antibody was measured in all cases. Results & Discussion: The eighty patients were randomly enrolled into 4 groups, 20 patients in each group. Their age ranged from 20 to 35 years and BMI ranged from 18 to 35. The percentage of +ve TPO Ab of the control group was 5% and of the recurrent abortion group was 20% and of the preterm labor group was 15% and of the IUGR group it was 5%. (P value 0.026) indicating statistically significant correlation between TPO Ab and recurrent unexplained abortion and preterm labor. Conclusion: The presence of (TPO) antibodies could be correlated to recurrent unexplained abortion and preterm labor. More studies are required to determine whether an intervention is needed to treat thyroid autoantibody positivity during pregnancy.

Terbutaline pump maintenance therapy after threatened preterm labour for reducing adverse neonatal outcomes.

After successful inhibition of threatened preterm labour women are at high risk of recurrent preterm labour. Terbutaline pump maintenance therapy has been used to reduce adverse neonatal outcomes. This review replaces an earlier Cochrane review, published in 2002, which is no longer being updated by the team. To determine the effectiveness of terbutaline pump maintenance therapy after threatened preterm labour in reducing adverse neonatal outcomes. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2014) and reference lists of retrieved studies. Randomised controlled trials comparing terbutaline pump therapy with alternative therapy, placebo, or no therapy after arrest of threatened preterm labour. Two review authors independently assessed the studies for inclusion and then extracted data as eligible for inclusion in qualitative and quantitative synthesis (meta-analysis). Four studies were included with a total of 234 women randomised. The overall methodological quality of the included studies was mixed; two studies provided very little information on study methods, there was high sample attrition in one study and in three studies the risk of performance bias was high. We found no strong evidence that terbutaline maintenance therapy offered any advantages over saline placebo or oral terbutaline maintenance therapy in reducing adverse neonatal outcomes by prolonging pregnancy among women with arrested preterm labour. The mean difference (MD) for gestational age at birth was -0.14 weeks (95% confidence interval (CI) -1.66 to 1.38) for terbutaline pump therapy compared with saline placebo pump for two trials combined. One trial reported a risk ratio (RR) of 1.17 (95% CI 0.79 to 1.73) for preterm birth (less than 37 completed weeks) and a RR of 0.97 (95% CI 0.51 to 1.84) of very preterm birth (less than 34 completed weeks) for terbutaline pump compared with saline placebo pump. We found no evidence that terbutaline pump therapy was associated with statistically significant reductions in infant respiratory distress syndrome, or neonatal intensive care unit admission compared with placebo. Compared with oral terbutaline, we found no evidence that pump therapy increased the rate of therapy continuation, or reduced the rate of infant complications or maternal hospital re-admissions. One study suggested that pump therapy resulted in significantly increased weekly cost/woman, $580 versus $12.50 (P < 0.01). No data were reported on long-term infant outcomes. We found no evidence that terbutaline pump maintenance therapy decreased adverse neonatal outcomes. Taken together with the lack of evidence of benefit, its substantial expense and the lack of information on the safety of the therapy do not support its use in the management of arrested preterm labour. Future use should only be in the context of well-conducted, adequately powered randomised controlled trials.

Proteomic analysis of cervical vaginal fluid proteins among women in recurrent preterm labor

Objective: Proteomic analysis of four cervical-vaginal fluid (CVF) proteins to identify biomarkers of recurrent preterm birth (rPTB) in at-risk women prior to onset of preterm labor.Methods: Nested case control study from 2007 to 2011 of women with prior spontaneous preterm birth(s) (PTB) who underwent serial CVF sampling. Mass spectrometry analysis was used and ELISA analysis was performed to validate candidates.Results: 108 patients were enrolled and 10 cases and 20 gestational age matched controls were analyzed after exclusions. Of 748 CVF proteins identified, 72 had statistically significant (p < 0.05) expression differences and 38 were highly differentially expressed (p < 0.01). Four candidate proteins were abundant and involved in immune/inflammatory response, but ELISA analysis did not confirm altered expression patterns.Conclusion: The lack of confirmation of potential biomarkers identified by mass spectrometry and ELISA demonstrates the challenges of validating PTB biomarkers and suggests that a panel of biomarkers would improve the predictive value of CVF testing.

The Effects of Progesterone Therapy on the Gestation Length and Reduction of Neonatal Complications in Patients who had Received Tocolytic Therapy for Acute Phase of Preterm Labor

BackgroundWhile tocolytic therapy can halt the process of delivery, some patients return before the 37th week of pregnancy with recurrence of preterm labor signs.ObjectivesThis study was designed to evaluate the efficacy of progesterone in the prolonging of gestation and reduction of neonatal complications.Material and MethodsIn a clinical trial in 2010, 110 singleton pregnant women admitted at Imam Reza Hospital, Mashhad, Iran, with the diagnosis of preterm labor were divided into three groups: 400 mg/d vaginal progesterone suppositories; 250 mg/w 17-alpha-hydroxyl-progestrone-caproate; and a control group with no additional treatment. After delivery, we assessed the duration between the first phases of labor to the recurrence of preterm labor. The neonatal complications, apgar score, birth weight, need for admission to NICU, and congenital malformations were compared between groups.ResultsThe mean gestational age was 34± 3 weeks in the first, 33.5 ± 3 weeks in the second and 32.5 ± 2 weeks in the control group. The duration of first phase of labor was 31 ± 17 days in the first, 36 ± 14 days in the second and 26 ± 22 days in the control group. The difference between study groups and the control group was significant (P < 0.005). The complications were lower in progesterone-receiving group in comparison to the control group.DiscussionThis study reveals that progesterone can significant reduce the rate of recurrent preterm labor and the several possible neonatal complications among women who had treated with tocolytics to suppress the acute phase.

What Do We Know about the Natural Outcomes of Preterm Labour? A Systematic Review and Meta‐Analysis of Women without Tocolysis in Preterm Labour

Current knowledge of the natural outcomes of untreated women in preterm labour is both incomplete and outcomes vary significantly between the available studies. The aim of this study was to systematically review outcomes of preterm labour without tocolysis and determine if outcome variation could be accounted for by differences in study populations. Such data could potentially assist in the interpretation of intervention trials that do not include a no-treatment arm. Included studies reported outcomes of women in clinically diagnosed preterm labour without tocolytic treatment between 1950 and 2011. Studies that were limited to preterm prelabour rupture of membranes, recurrent preterm labour or in which the women without tocolysis represented a potentially biased subgroup, or were not tocolysed because of contraindications were excluded. Study quality, design, and population characteristics were abstracted. Outcomes included pregnancy prolongation and the proportion of women undelivered at 48-72 h, 7 days, and term. Study characteristics associated with differing odds of preterm birth were explored through logistic regression. Three hundred and eighty-five citations were initially identified, of which 26 were included encompassing 1383 women. The percentage of patients who were undelivered at 48-72 hours was 62.8%, at 7 days 53.4% and 40.4% delivered at term, though the range was very wide. Characteristics associated with decreased odds of delivery were not consistent among reported outcome measures. Most women without tocolysis do not deliver within 7 days, although the range is very wide. The majority of this variation is unrelated to reported differences in study design or reported population characteristics.

39: Predictors of recurrent preterm birth: secondary analysis of maternal body fluid proteins among women in recurrent preterm labor

39: Predictors of recurrent preterm birth: secondary analysis of maternal body fluid proteins among women in recurrent preterm labor

Progesterone for Prevention of Recurrent Preterm Labor after Arrested Preterm Labor- A Randomized Controlled Trial

Background: Preterm birth is the major cause of neonatal mortality and morbidity. In developing countries, it’s a major health hazard. But there are very few evidence based interventions to prevent it. This study focus on prevention of preterm birth. Methods: A randomized controlled trial was undertaken in BP Koirala Institute of Health Sciences, where 60 patients were randomized into group 1 (n=29, weekly intramuscular Progesterone) and group 2 (n=31,no treatment) after the arrest of preterm labor with tocolysis. Their latency period till delivery and recurrence of preterm labor and neonatal outcomes were compared. Results: There was significant reduction in recurrence of preterm labor and increase in latency period in progesterone group. However neonatal outcomes were similar. Conclusion: Progesterone is useful in reducing the recurrence of preterm labor in a patient who had preterm labor.

Magnesium Sulfate for Preterm Labor and Preterm Birth

Obstetric Anesthesia Digest: December 2010 - Volume 30 - Issue 4 - p 202-203 doi: 10.1097/01.aoa.0000389572.25461.49

Exploring pregnancy following a pre-term birth or pregnancy loss

This is the first of two papers. The first paper outlines the literature review that informed the pilot study; the second describes the qualitative pilot study: stress, immunity and preterm birth pilot study (SIPP). The review examined qualitative research to understand the area of investigation and determine whether this corresponded with the findings of the pilot study. The SIPP study used semi-structured interviews exploring women's answers to a life events questionnaire as part of a larger quantitative prospective observational study, the stress, immunity and preterm birth (SIP) study. The SIP study examined the association between maternal stress, maternal immune response and pregnancy outcome in women with a history of recurrent idiopathic preterm labour. The review evolved into three broad themes: the impact of perinatal loss on a subsequent pregnancy; the preterm labour experience; and disenfranchised grief.

Progesterone supplementation for prevention of preterm labor: A randomized controlled trial

Abstract Objective To evaluate the efficacy of intramuscular progesterone in prevention of preterm labor in high risk cases. Design Randomized controlled trial. Setting Ain Shams Maternity hospital. Materials and methods Singleton pregnant women in their second trimester with a history of previous preterm labor were divided into two groups: progesterone group: received 17-α-hydroxy progesterone caproate (Cidolut depot) one dose of 250mg IM once weekly until 36weeks and placebo group: received standard dose of placebo IM per week. Follow up till delivery. Results The mean gestational age was 37.4±1.5 in progesterone group vs. 34.7±2.4 in placebo group ( P Conclusion Our findings support 17-α-hydroxy progesterone as a successful drug in the prevention and decreasing the rate of recurrent preterm labor.

462: Additive inhibitory effects of progesterone and sodium nitroprusside on uterine contractility during pregnancy

Progesterone (P4) suppresses uterine contractility (CTX) and is used to prevent recurrent preterm labor. Nitric oxide (NO) also inhibits CTX in experimental and clinical studies. Our objectives were to compare the effects of P4 to sodium nitroprusside (SNP, an NO donor) and their combination on human CTX of term/preterm and labor/nonlabor tissues to determine if there are additional effects of the two agents when used together.

An Examination of the Clinical Benefits and Cost-Effectiveness of Tocolytic Replacement Following Recurrent Preterm Labor

We examined pregnancy outcomes in women receiving nifedipine tocolysis having recurrent preterm labor (RPTL). Singleton gestations enrolled for outpatient nursing surveillance and prescribed nifedipine tocolysis were identified (N = 4748). Women hospitalized for RPTL at <35 weeks then resuming outpatient surveillance were included (N = 1366). Pregnancy outcomes of women resuming nifedipine (N = 830) were compared with those having an alteration in treatment to continuous subcutaneous terbutaline (N = 536). Overall, 56.7% (2692/4748) experienced RPTL. Half (50.7%) were stabilized and resumed outpatient surveillance with nifedipine or continuous subcutaneous terbutaline. Infants from women resuming nifedipine versus those with alteration of treatment to terbutaline were more likely to deliver at <35 weeks (28.0% versus 13.8%), weigh <2500 g (32.9% versus 20.3%), and require a stay in the neonatal intensive care unit (34.0% versus 23.1%), all P < 0.001. Alteration of tocolytic treatment following RPTL resulted in a decreased incidence of preterm birth and low birth weight, resulting in less admission to the neonatal intensive care unit and fewer nursery days.

Magnesium Sulfate for Preterm Labor and Preterm Birth

Approximately half of the more than 500,000 preterm births each year result from preterm labor. Tocolytic therapy continues to be the focus of treatment of these women. Although a variety of tocolytics are used in clinical practice, magnesium sulfate remains one of the most commonly used agents. Magnesium sulfate has also been the focus of recent research for its potential neuroprotective effects for neonates born preterm. Evaluation of 19 randomized clinical trials reveals that magnesium sulfate tocolysis does not reduce the frequencies of delivery within 48 hours, 7 days, or early/late preterm birth, and is not associated with improvements in newborn morbidities or mortality. No other tocolytic class resulted in improved newborn outcomes when compared with magnesium sulfate tocolysis. We conclude that it is appropriate to withhold tocolysis with magnesium sulfate or other agents from women presenting in preterm labor as newborn benefit has not been demonstrated with such treatment. If initiated to achieve time for antenatal corticosteroid administration, or for other acute reasons, treatment can be discontinued once these goals have been achieved or if labor subsides before then. Because brief pregnancy prolongation is unlikely to improve newborn outcomes after corticosteroid administration has been completed, it is appropriate to withhold magnesium sulfate tocolysis from women with recurrent preterm labor thereafter. If magnesium sulfate is given for neuroprotection, a protocol from one of the three major trials that have demonstrated benefits should be used.

Two Dose Regimens of Nifedipine for Management of Preterm Labor: A Randomized Controlled Trial

We compared two dose regimens of tocolytic oral nifedipine. Women with singleton pregnancies admitted in preterm labor (24 to 34 weeks) were randomized to high-dose (HD) nifedipine ( N = 49; 20 mg loading dose, repeated in 30 minutes, daily 120 to 160 mg slow-release nifedipine for 48 hours followed by 80 to 120 mg daily until 36 weeks) or low-dose (LD) nifedipine ( N = 53; 10 mg, up to four doses every 15 minutes, daily 60 to 80 mg slow-release nifedipine for 48 hours followed by 60 mg daily until 36 weeks). Uterine quiescence at 48 hours (primary outcome); delivery at 48 hours, 34 and 37 weeks; and recurrent preterm labor were similar. Gestational age at delivery was higher in HD (36.0 +/- 2.8 versus 34.7 +/- 3.7 weeks, P = 0.049). Rescue treatment was needed more in LD (24.5 versus 50.9%, odds ratio = 0.3; 95% confidence interval 0.1 to 0.7). Maternal adverse effects, birth weight, intensive care nursery admission, and composite neonatal morbidity were similar. However, neonatal mechanical ventilation was needed less and nursery stay was shorter in HD. HD nifedipine does not seem to have an advantage over LD in achieving uterine quiescence at 48 hours. Further studies should address the optimal dose and formulation of tocolytic nifedipine.