According to the WHO, preterm birth is defined as babies born alive before 37 weeks of pregnancy. Preterm births may occur due to spontaneous preterm labor or medical indications requiring early induction or cesarean delivery¹. In 2020, an estimated 13.4 million babies were born preterm, accounting for more than 1 in 10 births. In 2019, complications of preterm birth led to approximately 900,000 child deaths. Many survivors face long-term disabilities, including learning difficulties and visual or hearing impairments, highlighting the significant global health burden of preterm birth.Preterm birth is the leading cause of infant mortality and long-term disability in children, with survival outcomes varying by income level². In low-income settings, half of the babies born at or below 32 weeks die due to a lack of basic, cost-effective care, while in high-income countries, nearly all survive. Middle-income settings face challenges with suboptimal use of technology, leading to a higher burden of disability among preterm survivors. Compared to term-born infants, preterm babies are at increased risk of neurodevelopmental impairments, gastrointestinal complications, cerebral palsy, sensory deficits, learning disabilities, and respiratory illnesses³. The long-term morbidity of preterm birth extends into later life, imposing significant physical, psychological, and economic burdens.Several risk factors contribute to preterm birth, including sociodemographic factors such as ethnicity, advanced maternal age, smoking, and low education levels. Obstetric factors like primiparity and inadequate antenatal care increase the risk of preterm delivery, which can be managed with tocolytic agents such as beta-agonists, calcium channel blockers, and prostaglandin inhibitors⁴. Magnesium sulfate, a first-line tocolytic, inhibits myometrial contraction by reducing acetylcholine release, though its effectiveness remains controversial⁵.Due to concerns over maternal and fetal complications, magnesium sulfate is often replaced by nifedipine, a calcium channel blocker that inhibits calcium influx into smooth muscle cells, preventing uterine contractions. Nifedipine is preferred due to its oral administration, better tolerability, and fewer side effects, although severe complications such as dyspnea, hypoxia, myocardial infarction, and fetal death have been reported in rare cases⁶. Despite its risks, nifedipine remains a widely used tocolytic for managing preterm labor⁷.

AIM

The aim of study is comparison of safety and effectiveness of intravenous Mgso4 and oral nifedipine in treatment of preterm labour.

This prospective randomized controlled trial was conducted in the Department of Obstetrics and Gynaecology at Mathuradas Mathur Hospital, affiliated with Dr. S. N. Medical College, Jodhpur, Rajasthan, India. The study was carried out from the time of ethical committee approval until the completion of the required sample size. The study population included pregnant women admitted to the labor room ward of MDM Hospital who met the specified inclusion and exclusion criteria.

This study included pregnant women aged 28–36+6 weeks with intact membranes, cervical dilation <3 cm, cervical effacement <75%, and at least four uterine contractions in 20 minutes, each lasting 40 seconds. Exclusion criteria included maternal conditions like chorioamnionitis, antepartum hemorrhage, hypertensive disorders, amniotic fluid abnormalities, previous cesarean section, cardiac or renal disease, uncontrolled diabetes, hyperthyroidism, and pulmonary disorders. Contraindications for magnesium sulfate (myasthenia gravis, heart block, renal disease, recent MI) and nifedipine (hypotension, heart failure, aortic stenosis) were also considered. Fetal exclusion factors included fetal death, non-reassuring fetal heart tracing, congenital abnormalities, fetal growth restriction, erythroblastosis fetalis, and multiple pregnancies

Table 1: Distribution of cases according to age

There was no statistically significant difference in age distribution between the groups (P=0.9921), with Group A having more individuals aged 21–25 years (52.5%), while Group B had higher proportions in the 19–20 years (27.5%) and ≥31 years (12.5%) age ranges.

There was no statistically significant difference between the groups in terms of gravida distribution (P=0.8179) or mode of delivery (P=0.1658), with similar proportions of primi- and multi-gravida, and a higher prevalence of normal delivery in both groups.

Table 2: Distribution of cases according to side effect

Group A had higher incidences of drowsiness (22.5%) and flushing (25%), while Group B experienced dizziness (5%) and palpitations (5%), with similar rates of headache and nausea/vomiting, and a statistically significant difference (P=0.0118).

Table 3: Distribution according to neonatal morbidity

Neonatal morbidity was higher in the MgSO₄ group, with increased cases of hypothermia (17.5% vs. 10%), RDS (15% vs. 7.5%), sepsis (7.5% vs. 2.5%), feeding problems (25% vs. 15%), and hyperbilirubinemia (20% vs. 15%) compared to the Nifedipine group.

Table 4: Distribution according to cervix dilatation

Group B had a significantly higher percentage of individuals with 1 cm cervical dilatation (65% vs. 35%) compared to Group A, with a p-value of 0.027, while no significant difference was observed for 2 cm and 3 cm dilation.

Table 5: Distribution according to cervix Effacement

Group B had a significantly higher percentage of individuals with 25% effacement (72.5% vs. 47.5%), while Group A had more cases with 50% effacement (42.5% vs. 10%), with a p-value of 0.022 indicating statistical significance.

Table 6: Duration of Prolongation

Group-B had a higher proportion of cases with prolongation beyond 72 hours, while Group-A had more cases under 48 hours, with a p-value of 0.021 indicating a trend toward significance.

Table 7: success of acute tocolysis

Group-B had a significantly higher proportion of cases lasting more than 48 hours (83%) compared to Group-A (62%), with a p-value of 0.045 indicating statistical significance.

Table 8: Distribution according to APGAR Score

Group-B had significantly better 5-minute APGAR scores (≥7 in 62.5%) compared to Group-A (≥7 in 30%), with a p-value of 0.003 indicating a statistically significant difference.

The mean age of cases in MgSo4 group is 24.13 years with majority of cases are in age group 21-25 years (52.5%) followed by 25% in 26-30 years age group, whereas Nifedipine Group mean age of cases is 24.0 years with majority of cases are in age group 21-25 years (40%) followed by 27.5% in age group 19-20 years. Statistically we found no significant difference in mean age of cases in both groups. In a study conducted by Tabassum S et al⁸ 2016, the mean age of women in nifedipine group was 29 years and in MgSO4 was 30 years.

According to gravida we found that in both groups majority of cases are multi gravida, with statistically no significant difference in gravida among both groups (p-value 0.8179).  In Bhat et al⁹ study Most of patients in Nifedipine group are multipara (22) 55% and MgSO4 group are primigravida (21)52.5% using chi-square test with p-value 0.502 (not significant). 

In both groups majority of women delivered normally followed by 10% in MgSo4 group and 2.5% in Nifedipine group delivered through c-section.

Here, we found statistically significant difference in side effect among two groups (p-value 0.018). In MgSo4 group most prevalent side effects are Flushing (25%), Drowsiness (22.5%), Nausea / Vomiting (12.5%)and headache (10%). In Nifedipine group most prevalent side effects are headache (12.5%), dizziness (5%), flushing (5%), Nausea / Vomiting (5%), palpitation (5%) and hypotension (2.5%). Comparable to our results  Larmon and colleagues¹⁰ also reported that Patients in the magnesium sulfate group had more side-effects in the form of nausea and vomiting and they were more likely to have another tocolytic agent. 

The occurrence of neonatal morbidity in MgSo4 group and Nifedipine group with more neonatal morbidity in MgSo4 group. MgSo4 group reported hypothermia in 17.5% of cases, compared to 10% in Nifedipine group. In MgSo4 group, 15% of individuals experienced RDS, compared to 7.5% in Nifedipine group. MgSo4 group reported sepsis in 7.5% of cases, while Nifedipine group reported 2.5%. In MgSo4 group, 25% have feeding problem, while 15% in Nifedipine group. In MgSo4 group, 20% of neonates have hyperbilirubinemia, compared to 15% in Nifedipine group.  Some authors Wolf et al¹¹ and Cox et al¹² reported that MgSO4 may lead to respiratory suppression in neonates. 

In our results we found a significant difference (p-value 0.027) in cervix dilation in two groups with majority of women have cervix dilated to 2 cm (60%) followed by 5% have cervix dilation to 3 cm in MgSo4 group. In Nifedipine group majority of women have cervix dilated to 1 cm (65%) followed by 32.5% have cervix dilation to 2 cm.

Similarly, we found statistically significate difference (p-value 0.022) in cervix Effacement in both groups. In MgSo4 group 47.5% have cervix Effacement of 25% followed by 42.5% have cervix Effacement of 50% and 10% have cervix Effacement up to 75%. In Nifedipine group maximum women (72.5%) cervix Effacement 25% followed by 17.5% have cervix Effacement up to 75% and 10.5 have cervix Effacement up to 50%.

Here, we found that in Nifedipine group duration of prolongation is highest up to 72 hours to one week (34%) followed by 31% have prolongation up to 48-72 hours, 18% have prolongation more than one week and 17% have prolongation less than 48 hours. And, in MgSo4 group, 45% of cases had a prolongation period of less than 48 hours followed by 27.5% have prolongation period between 48-72 hours, 17.5% have prolongation of 72 hours to one week and only 10% have prolongation more than one week. The p-value of 0.021 suggests a trend toward a significant difference in prolongation periods between the two groups. Here, we also found that success of tocolysis for more than 48 hours is maximum in Nifedipine group (83%) compared to 62% in MgSo4 group. We found a statistically significant difference in success of tocolysis in Nifedipine group compared to MgSo4group (p-value 0.045) In their Bachnas et al¹³ reported that nifedipine was more effective than MgSO4 in delaying labor for more than 48 hours.

 Nifedipine was successful in prevention of labour for 48 hours (primary tocolytic effects) in 85% of patients and MgSO4 in 80% patients. Nifedipine was efficient in delaying delivery up to 7 days (secondary tocolytic effects) in 80% of patients and MgSO4 was efficient in 67.5% of patients. Although from the above, nifedipine appears to be a better tocolytic when compared to MgSO4, statistically, it is not significant (p value is 0.854). Nikbakht et al¹⁴ 2014 conducted a similar study and both drugs were equally effective in prevention of labour and delaying delivery >7 days, 56% vs. 64% in the nifedipine and magnesium sulphate groups, and the days gain in utero was no statistically different in two groups.

The mean APGAR score at 5 minute in Nifedipine group is 6.75 with majority (62.5%) have APGAR score >7. In MgSo4 group mean APGAR score is 5.13 with majority (70%) have APGAR score <7. The p-value of 0.003 indicates a statistically significant difference in APGAR scores between the two groups, with Nifedipine group showing better outcomes. Khooshideh et al¹⁵ 2017, also observed that there were no statistically significant differences in one-minute and fiveminute Apgar scores in neonates.

Statistically significant difference in neonatal death rates between the two groups (p-value 0.3048) with 7.5% death in MgSo4 group and only 2.5% death in Nifedipine group. 

In conclusion, our data in this study showed that oral nifedipine is as effective as magnesium sulphate with regard to inhibition of preterm labour. Although, nifedipine is better than MgSO4 when their primary tocolytics effects (who has not delivered till 48 hours) and secondary tocolytic effects (who has not delivered till 7 days) are compared but it is not statistically significant. Although neonates who were exposed to MgSO4 in utero had more NICU admission when compared to nifedipine group which is significant, we have not found any significant difference in the incidence of respiratory distress syndrome. We conclude that as nifedipine with its easy availability, least side effects profile, low cost, ease of administration and with less intensive monitoring, can be considered as better option for management of preterm labour. No matter which tocolytic agent the clinician chooses, the evidence supports the use of short-term tocolytic drugs to prolong pregnancy for at least 48 hours to allow for administration of antenatal steroids and to allow for transport of the mother to a tertiary care facility. As this study comprised a small sample, large randomised studies are required to prove the efficacy of the tocolytics.

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