European Journal of Cardiovascular Medicine

Pregnancy extending beyond the expected date of delivery continues to be one of the most debated and clinically challenging areas in obstetrics. Approximately 4–15% of all pregnancies go beyond 40 weeks of gestation, with an average incidence of 10%. The risk of fetal morbidity and mortality increases as gestation advances beyond term. The American College of Obstetricians and Gynecologists (ACOG) defines early term as 37⁰/₇–38⁶/₇ weeks, full term as 39⁰/₇–40⁶/₇ weeks, late term as 41⁰/₇–41⁶/₇ weeks, and post-term as ≥42⁰/₇ weeks of gestation. Pregnancies between 40 and 42 weeks are categorized as prolonged pregnancies.^[1]

The extension of pregnancy beyond term is associated with both maternal and fetal complications. Maternal risks include prolonged labour, increased incidence of labour dystocia, perineal injuries due to macrosomia, and a higher likelihood of operative or cesarean deliveries. Fetal complications include placental insufficiency, oligohydramnios, meconium aspiration, fetal distress, macrosomia, and shoulder dystocia. The perinatal mortality rate doubles after 42 weeks and increases four- to six-fold by 44 weeks.^[2]

The underlying etiology of post-dated pregnancy is multifactorial. Common causes include inaccurate dating due to irregular menstrual cycles, familial or genetic predisposition, maternal obesity, placental sulfatase deficiency, and endocrine abnormalities such as deficiency of estrogen precursors from the fetal adrenal gland. The phenomenon of “placental aging,” characterized by calcification, infarction, and reduced perfusion, contributes to fetal hypoxia and growth restriction.

The management of post-dated pregnancy remains controversial. Obstetricians often face the dilemma of choosing between expectant management with vigilant antepartum surveillance or elective induction of labour to minimize potential complications. Several studies, including large randomized controlled trials and meta-analyses, have demonstrated that routine induction at or beyond 41 weeks reduces perinatal morbidity and mortality without significantly increasing cesarean section rates.^[3]

Fetal surveillance methods such as non-stress test (NST), biophysical profile (BPP), amniotic fluid index (AFI), and Doppler studies play crucial roles in identifying fetuses at risk. An AFI below 5 cm indicates oligohydramnios, a critical sign warranting intervention. The use of prostaglandins for cervical ripening and oxytocin for induction has revolutionized safe labour management in post-dated pregnancies.^[4]

Aim

To compare the maternal and fetal outcomes between spontaneous and induced labour among post-dated pregnancies.

Objectives

1. To study and compare the rate and duration of labour in spontaneous and induced labour among post-dated pregnancies.
2. To evaluate and compare maternal complications such as mode of delivery, perineal injuries, and postpartum haemorrhage between both groups.
3. To assess fetal outcomes including Apgar scores, meconium aspiration, NICU admissions, and perinatal mortality in both groups.

Source of Data: The study included pregnant women who had crossed the expected date of delivery and were admitted to the Department of Obstetrics and Gynaecology, Basaveshwar and Sangameshwar Teaching and General Hospitals attached to M.R. Medical College, Kalaburagi.

Study Design: A prospective interventional study.

Study Duration: October 2017 to April 2019.

Sample Size: 100 pregnant women beyond 40 weeks of gestation.

Inclusion Criteria:

• Pregnant women beyond 40 weeks of gestation with reliable LMP or EDD confirmed by first-trimester ultrasound.
• Singleton pregnancies with vertex presentation.

Exclusion Criteria:

• Obstetric complications such as oligohydramnios, malpresentations, placenta previa, abruptio placentae, gestational hypertension, or diabetes.
• Pregnancies associated with medical disorders or fetal anomalies.
• Unconfirmed gestational age.

Procedure and Methodology: After obtaining informed consent, detailed history, general, systemic, and obstetric examinations were performed. All women underwent routine investigations and Non-Stress Test (NST). Ultrasound was used to assess fetal presentation, estimated fetal weight, AFI, placental localization, and grading.

Group I (Spontaneous Labour): Women with spontaneous onset of labour were monitored using continuous CTG.

Group II (Induced Labour): Women not in labour after 40 weeks were induced after confirming fetal wellbeing by modified BPP.

When Bishop’s Score <6, cervical ripening was performed using Dinoprostone (PGE₂) gel 0.5 mg, followed by oxytocin infusion if required.

When Bishop’s Score ≥6, artificial rupture of membranes (ARM) and oxytocin induction were carried out.

Labour progress was closely monitored; mode of delivery, duration of labour, and indications for cesarean section were recorded. Neonatal parameters such as Apgar score, NICU admissions, and complications (meconium aspiration, asphyxia) were documented. Placentae were examined for calcification and infarction.

Sample Processing: Clinical data were recorded in structured proformas and entered into a master chart for analysis.

Statistical Methods: Data were analyzed using SPSS version 20.0. Quantitative data - duration of labour were compared using Student’s t-test. Qualitative variables, mode of delivery, maternal and fetal complications were analyzed using Chi-square test or Fisher’s exact test as applicable. A p-value <0.05 was considered statistically significant.

Data Collection: All relevant maternal and neonatal data, including obstetric history, intrapartum details, and neonatal outcomes, were collected prospectively and verified from hospital records.

Table 1: Overall comparison of key maternal & fetal outcomes (Spontaneous vs Induced; N=100)

Table 1 compares the overall maternal and fetal outcomes between spontaneous and induced labour groups. The cesarean section rate was markedly higher in the induced group (50%) compared to the spontaneous group (16%), a statistically significant difference (χ² = 13.07, p = 0.0003; RR 0.32, 95% CI 0.16–0.64). Conversely, vaginal delivery was more frequent in spontaneous labour (70%) than in induced labour (42%), which was also significant (χ² = 8.64, p = 0.0033; RR 1.67, 95% CI 1.14–2.45). Operative vaginal deliveries were slightly more common in spontaneous cases (14%) than in induced (8%), though not statistically significant (p = 0.34). Neonatal outcomes, including NICU admission (12% vs 10%), meconium aspiration syndrome (10% vs 10%), and low Apgar scores at 5 minutes (12% vs 10%), were comparable between both groups (p > 0.05). Perinatal mortality was low in both groups (2% vs 4%), with no significant difference (p = 1.00).

Table 2: Labour progress: rate and duration (N=100)

*Mean and SD derived from your category counts using mid-interval values (<6 h = 4.5; 7–12 h = 9.5; 13–18 h = 15.5; >18 h = 19.5).

Table 2 evaluates the rate and duration of labour across both groups. A larger proportion of spontaneous labours (86%) were completed within 12 hours compared to 78% in induced labours, though the difference was not statistically significant (χ² = 1.08, p = 0.30; RR 1.10, 95% CI 0.92–1.33). However, the mean duration of labour was significantly longer in the induced group (10.48 ± 3.50 hours) than in the spontaneous group (8.72 ± 3.81 hours) with a mean difference of −1.76 hours (95% CI −3.19 to −0.33; p = 0.018).

Table 3: Maternal complications by group (N=100)

Table 3 presents maternal complications in both groups. The incidence of perineal tears was identical in spontaneous and induced groups (4% each; RR 1.00, 95% CI 0.15–6.70; p = 1.00). Postpartum haemorrhage occurred slightly more often in induced labour (12%) than in spontaneous (10%), but the difference was statistically insignificant (p = 0.75). No postpartum infections were reported in either group. The requirement for blood transfusion was marginally higher in the spontaneous group (6%) than in the induced group (4%), again showing no statistical significance (p = 1.00).

Table 4: Fetal outcomes by group (N=100)

Table 4 assesses fetal outcomes across both study groups. The proportion of neonates with low Apgar scores at one minute was higher in spontaneous labour (64%) than in induced labour (48%), but the difference was not statistically significant (χ² = 2.53, p = 0.11; RR 1.33, 95% CI 0.92–1.92). At five minutes, Apgar <7 occurred in 12% versus 10%, respectively, with no meaningful difference (p = 0.75). The incidence of meconium aspiration syndrome was identical in both groups (10%), as was NICU admission (12% vs 10%), and perinatal mortality remained low (2% vs 4%), with no statistical significance (p = 1.00).

Table 1 (Overall maternal & fetal outcomes). Cohort shows a markedly higher cesarean rate with induction (50%) versus spontaneous labour (16%) (RR 0.32, 95% CI 0.16–0.64; p=0.0003), alongside a higher vaginal delivery rate in the spontaneous group (70% vs 42%; p=0.0033). This pattern aligns with large observational series in which later gestational age and need for augmentation are associated with increasing intrapartum intervention and cesarean delivery (especially for non-reassuring FHR and arrest disorders) Karmakar S et al.(2021)^[6] However, randomized and meta-analytic evidence in post-term populations has not consistently shown induction to raise cesarean risk; in fact, induction at ≥41 weeks can be neutral or even protective versus expectant management Roy M et al.(2025)^[7]. Two factors likely explain the contrast: (i) your induced group includes a greater burden of unfavourable cervices (reflected by your protocol using PGE₂ when Bishop <6), and (ii) real-world selection (induction often chosen for subtle concerns) increases background risk—both known drivers of higher operative delivery. Importantly, neonatal outcomes were comparable: NICU admission (12% vs 10%), 5-min Apgar <7 (12% vs 10%), MAS (10% vs 10%), and perinatal mortality (2% vs 4%) showed no significant differences (all p≥0.75). This mirrors post-term RCTs and meta-analyses where well-monitored induction does not worsen perinatal endpoints and may reduce rare stillbirths without excess neonatal morbidity Jeer B et al.(2023)^[8]. Regional Indian studies of post-dated pregnancies also report broadly similar neonatal profiles, with between-group differences largely driven by intrapartum management rather than baseline fetal condition Ferdaushi Z et al.(2022)^[9].

Table 2 (Labour progress). Although completion within 12 h was not statistically different (86% spontaneous vs 78% induced; p=0.30), mean labour duration was ~1.8 h longer with induction (MD −1.76 h favouring spontaneous; p=0.018). Prolonged latent/active phases and longer second stages with increasing gestational age and oxytocin exposure are well described Laikemariam M et al.(2023)^[10]. Trials in post-term populations note that when induction is initiated with an unfavourable cervix, total labour time increases even when ultimate delivery mode and neonatal outcomes are acceptable Yadav K et al.(2020)^[11]. Your pattern is consistent with this physiology and with Indian single-centre experiences where induction lengthens labour but does not materially worsen perinatal endpoints under continuous CTG and timely decision-making Hong J et al.(2023)^[12].

Table 3 (Maternal complications). Rates of perineal tears (4% vs 4%), postpartum haemorrhage (10% vs 12%), infection (0% both), and transfusion (6% vs 4%) were statistically similar (all p≥0.75). This echoes RCT and meta-analytic data indicating that, in appropriately selected and monitored post-dated pregnancies, induction does not increase overall maternal morbidity Singh N et al.(2020)^[13]. Observational analyses show that the maternal risk signal at later gestations relates more to dystocia/macrosomia and prolonged labour than to induction per Khanam KA et al.(2023)^[14] consistent with your finding that the mode of delivery differs by group, whereas complication rates do not.

Table 4 (Fetal outcomes). Early adaptation (Apgar <7 at 1 min) trended higher after spontaneous onset (64% vs 48%; p=0.11), but by 5 min scores converged (12% vs 10%; p=0.75), and serious outcomes (MAS 10% each; NICU 12% vs 10%; perinatal deaths 2% vs 4%) were comparable. Post-term physiology—oligohydramnios, thicker meconium, and cord compression—can transiently depress early Apgar despite similar 5-min recovery under modern intrapartum care Salam S et al.(2024)^[15]. Your equivalence in MAS and NICU mirrors both RCTs and local Indian data sets, where protocolized surveillance (NST/BPP), timely amniotomy with meconium preparedness, and decisive operative delivery mitigate perinatal risk across management strategies Turkmen S et al.(2024)^[16].

The present prospective interventional study compared maternal and fetal outcomes between spontaneous and induced labour among post-dated pregnancies. The results demonstrated that the rate of cesarean section was significantly higher in the induced group, whereas spontaneous labour was associated with a higher rate of successful vaginal delivery. However, no statistically significant difference was observed in maternal complications such as perineal tears, postpartum haemorrhage, or blood transfusion between the two groups. Similarly, neonatal outcomes—including Apgar scores, meconium aspiration, NICU admission, and perinatal mortality—were comparable across both groups. Although induction prolonged the mean duration of labour, it did not adversely affect fetal outcomes. The findings suggest that careful selection of patients, timely induction with appropriate cervical ripening agents, and vigilant intrapartum monitoring can minimize risks and achieve favourable maternal and perinatal outcomes. Therefore, induction of labour in post-dated pregnancies, when clinically indicated and properly managed, remains a safe and effective strategy to reduce potential complications associated with prolonged gestation.

LIMITATIONS OF THE STUDY

1. The study was conducted at a single tertiary care centre with a relatively small sample size of 100, which may limit generalizability of results.
2. Cervical status prior to induction was not stratified in sub-analysis, which could have influenced the success rate of vaginal delivery.
3. Certain confounding factors such as maternal BMI, previous obstetric history, and psychosocial parameters were not controlled for.
4. Neonatal outcomes were assessed only during the immediate postpartum period; long-term neonatal morbidity and neurodevelopmental outcomes were not evaluated.
5. The study did not employ blinding or randomization, introducing potential selection bias between spontaneous and induced groups.

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