Amniotic fluid does far more than cushion the fetus. Its volume in late pregnancy depends largely on fetal urine output, which in turn mirrors renal perfusion and, indirectly, placental function. A falling fluid volume is therefore read by most obstetricians as a possible sign of a fetus under strain. On ultrasound the fluid is usually measured as the amniotic fluid index (AFI), the sum of the deepest pockets in four quadrants, and an AFI of 5 cm or less is the threshold most widely used in Pakistani units to label oligohydramnios (1).

Local evidence on what this label means for the newborn is far from uniform. At Khyber Teaching Hospital, Peshawar, women with an AFI below 5 cm had more labour inductions and cesarean sections than women with normal fluid, yet birth weight, Apgar scores and NICU admission did not differ between the groups (2). A later cross-sectional study from the same hospital recorded a low Apgar score in 17% and NICU admission in only 8% of neonates (3). In contrast, a case-control study from Islamabad reported cesarean delivery in 46%, a low Apgar score in 38% and NICU admission in 30% of oligohydramnios pregnancies, along with six stillbirths (4). Studies from Bahawalpur and Lahore likewise describe neonatal complications in roughly two of every five affected pregnancies (5,6). One reason for these contrasting figures may be that oligohydramnios is often part of a wider picture: an Islamabad cohort found maternal anaemia in 44% of affected women, cesarean delivery in 81.6% and low birth weight in 44.5% of their babies (7).

Pakistani investigators have also explored ways of refining risk within this group. Doppler cerebroplacental ratio showed high accuracy in predicting poor postnatal outcome in women with isolated oligohydramnios (8), while a randomized trial found that adding enoxaparin to conventional treatment did not improve borderline fluid volumes (9). At the community level, the multinational First Look trial found the highest prevalence of oligohydramnios at its Pakistani site, and affected women had roughly fivefold higher odds of stillbirth than women with normal fluid (10).

These findings matter in a country where the stillbirth rate is about 30 per 1000 births and perinatal mortality has stayed close to 75 per 1000 births over the past decade (11,12).

Most local studies treat oligohydramnios as a single category, although an AFI of 4.5 cm and one of 1.5 cm may represent very different degrees of fetal compromise. Data that separate severe from moderate reduction are scarce, particularly from tertiary units in Khyber Pakhtunkhwa. The present study was therefore designed to describe neonatal outcomes in term pregnancies with oligohydramnios at our hospital and to compare outcomes between women with severe (AFI ≤2.0 cm) and moderate (AFI 2.1–5.0 cm) fluid reduction.

This cross-sectional study was conducted in the Department of Obstetrics and Gynecology, Moulvi Ameer Shah Memorial Hospital, Peshawar, Pakistan, over the period of six months.. Records of all women delivered with an ultrasound-confirmed AFI of 5 cm or less were retrieved, giving 208 eligible records. Term was defined as 37 completed weeks or more, so twenty records at 36 weeks were excluded and 188 singleton term pregnancies (37–40 weeks) formed the study population. AFI was measured by the four-quadrant technique, and women were divided into a severe group (AFI ≤2.0 cm, n=49) and a moderate group (AFI 2.1–5.0 cm, n=139). Data recorded for each woman included maternal age, parity, gestational age, AFI and mode of delivery, while neonatal data comprised birth weight, Apgar scores at 1 and 5 minutes, NICU admission, meconium-stained liquor, stillbirth and neonatal death. Low birth weight was defined as less than 2.5 kg and a low 5-minute Apgar score as less than 7. Data were entered and analysed using SPSS version 26.0 (IBM Corp., Armonk, NY, USA). Continuous variables were expressed as mean ± standard deviation and compared with Welch’s t test, with Cohen’s d reported as the effect size. Categorical variables were expressed as frequency and percentage and compared with the two-sided Fisher’s exact test, or the chi-square test for the three-category delivery mode. Because several outcomes contained zero cells, odds ratios with 95% confidence intervals were estimated using the Haldane–Anscombe correction (adding 0.5 to each cell), and multivariable logistic regression was not attempted since complete separation makes maximum-likelihood estimates non-estimable. The relationship between AFI and neonatal parameters was examined with Pearson’s and Spearman’s correlation coefficients. A p value below 0.05 was considered statistically significant.

A total of 188 term pregnancies were analyzed. The mean maternal age was 29.96 ± 3.59 years, mean parity 2.32 ± 1.14 and mean gestational age 38.47 ± 1.04 weeks. The mean AFI was 3.24 ± 1.14 cm (range 1.5–4.9 cm), and 49 women (26.1%) fell into the severe group. Women with severe oligohydramnios were older, of higher parity and delivered later in gestation than those with moderate reduction. Their babies were lighter by about 610 g on average and had clearly lower Apgar scores at both 1 and 5 minutes. All differences were significant, and the effect sizes for birth weight and Apgar scores were very large (Cohen’s d above 3), as shown in Table 1.

Table 1. Maternal and neonatal characteristics by severity of oligohydramnios (n=188)

Values are mean ± standard deviation. Welch’s t test; d = Cohen’s d (absolute value).

Spontaneous vaginal birth was the commonest mode of delivery overall (110, 58.5%), followed by cesarean section (68, 36.2%) and instrumental delivery (10, 5.3%). The distribution was sharply different between groups (χ²=116.95, df=2, p<0.001). Every woman in the severe group was delivered by cesarean section, whereas almost four in five women with moderate reduction delivered vaginally (Table 2). The odds of cesarean delivery were therefore markedly higher with severe oligohydramnios (OR 611.8, 95% CI 36.2–10331.6).

Table 2. Mode of delivery by severity of oligohydramnios

Chi-square test of independence, χ²=116.95, df=2.

Neonatal morbidity was concentrated in the severe group (Table 3). All 49 neonates in this group were admitted to the NICU, compared with 28 (20.1%) in the moderate group, and meconium-stained liquor was seen in 47 (95.9%) against only 4 (2.9%). Low birth weight was present in every neonate with severe reduction but in just 14 (10.1%) of those with moderate reduction. A 5-minute Apgar score below 7 was recorded in 24 (49.0%) neonates of the severe group and in none of the moderate group. The nine stillbirths (18.4%) and eight neonatal deaths (16.3%) all belonged to the severe group. Each comparison was significant on Fisher’s exact test. The absolute risk differences ranged from 16.3 percentage points for neonatal death to 93.0 points for meconium staining. The confidence intervals around the odds ratios were very wide because of zero or near-zero cells and should be read as indicating the direction and strength of association rather than precise effect sizes.

Table 3. Adverse neonatal outcomes by severity of oligohydramnios

*Haldane–Anscombe corrected odds ratio. p values from two-sided Fisher’s exact test.

AFI correlated positively and strongly with birth weight (r=0.984) and with Apgar scores at 1 minute (r=0.944) and 5 minutes (r=0.935). It correlated negatively with gestational age (r=−0.721), meaning that lower fluid volumes were found in pregnancies that had advanced further towards 40 weeks. Spearman’s coefficients gave the same pattern, and all correlations were significant (Table 4).

Table 4. Correlation of amniotic fluid index with neonatal parameters and gestational age (n=188)

This study shows that, among term pregnancies already labelled as oligohydramnios, risk was far from uniform. Neonates of mothers with an AFI of 2 cm or less carried almost the entire burden of adverse outcome, including every stillbirth and neonatal death, while outcomes with moderate reduction were comparatively reassuring. Earlier Pakistani work points in the same direction. Siraj et al., studying uncomplicated term pregnancies in Okara and Karachi, found that isolated oligohydramnios was associated with low birth weight in 83%, meconium staining in 54.7% and cesarean section in 72.6% of cases, although Apgar scores and intrauterine death did not differ significantly from controls (13). Ahmad and Munim at the Aga Khan University Hospital likewise found lower birth weight and more inductions and cesarean sections, without excess low Apgar scores or NICU admission (14). Our moderate group behaved much like these cohorts, whereas the severe group did not, which suggests that pooling all women with an AFI below 5 cm may dilute a real risk concentrated at the lowest values. The overall morbidity in our cohort was higher than in several local series. Our NICU admission rate of 41.0% is five times the 8% reported from Khyber Teaching Hospital (3) and higher than the 30% seen in Islamabad (4). Amir et al. showed that women with oligohydramnios induced with misoprostol in Islamabad could deliver vaginally, but their babies had more meconium staining, lower Apgar scores and more NICU admissions than babies of women with normal fluid (15). In Peshawar, Nazir et al. found that one-third of term neonates were admitted to the NICU and that a pathological admission cardiotocogram strongly predicted a low Apgar score (16). Part of the difference from other units probably reflects case mix, since our hospital receives referred and often late-booking women, but local admission policy also plays a role, as some units routinely observe every baby born by cesarean section after oligohydramnios. Meconium staining was almost universal in the severe group. This is clinically important because meconium-stained liquor was the leading risk factor for birth asphyxia in a case-control study from Multan, being present in 80% of asphyxiated neonates compared with 40% of controls (17). In Karachi, thick meconium was linked to low Apgar scores, emergency cesarean section and meconium aspiration syndrome (18). The pattern in our data, with meconium, low 5-minute Apgar scores and NICU admission clustering in the same women, fits this pathway of reduced fluid, cord compression and intrapartum hypoxia. The link between severe oligohydramnios and fetal growth was the most consistent signal. All neonates in the severe group weighed less than 2.5 kg, and AFI correlated strongly with birth weight. Very low fluid is often a late expression of placental insufficiency, and in Pakistan this sits on top of a heavy background burden of growth restriction that is easily missed; in a Karachi cohort the WHO fetal growth chart identified considerably more term small-for-gestational-age babies than INTERGROWTH-21st (19). Analysis of the PRISMA cohort showed that nearly half of Pakistani newborns are small and vulnerable, with term small-for-gestational-age birth the commonest category and a fourfold higher risk of neonatal death (20). Maternal anaemia, present in more than three-quarters of term mothers in a recent Karachi study, was also significantly associated with low birth weight (21). Taken together, these data suggest that in women with severe reduction the real question may be fetal growth rather than fluid volume alone, and growth and Doppler assessment should accompany the AFI. Stillbirth and neonatal death rates in the severe group were striking. In twelve high-volume facilities in Karachi, fewer than eight antenatal visits independently increased the risk of stillbirth (22), and a NICU audit from Lahore reported a case-fatality rate close to 46% for birth asphyxia (23). Death audits in rural Sindh have shown that delays in recognising danger signs and in receiving adequate care account for most stillbirths and neonatal deaths (24). For our population, earlier booking, a third-trimester scan for every woman and prompt referral of those with an AFI of 2 cm or less are practical steps. Maternal hydration, which raised the AFI by an average of 4.5 cm in a Lahore study, may also have a place in selected women while delivery is planned (25). This study has some limitations. It was retrospective and conducted at a single centre, and only women with oligohydramnios were included, so the excess risk relative to normal amniotic fluid volume could not be estimated. Information on maternal comorbidities, Doppler indices and fetal growth centiles was not available, and multivariable adjustment was not feasible because several outcomes occurred in only one group. For the same reason the confidence intervals around the odds ratios were wide. The follow-up period for neonatal outcomes was limited to the hospital stay. Prospective multicentre studies that include women with normal fluid volume would strengthen these findings.

       In term pregnancies with oligohydramnios, adverse neonatal outcome was concentrated in women with an AFI of 2 cm or less, who had lighter babies, lower Apgar scores, universal NICU admission and all recorded perinatal deaths. Severe reduction should prompt growth and Doppler assessment and senior-led delivery planning, and an AFI of 2 cm or less may serve as a practical local threshold for heightened surveillance and timely referral.

       Funding: This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

       Conflict Of Interest: The authors declare no conflict of interest.

       Acknowledgements: The authors thank the staff of the Department of Obstetrics and Gynecology and the record section of Moulvi Ameer Shah Memorial Hospital for their help in retrieving the data.

        Author Contributions: Maliha Fazal: conception, design and data collection; Huma Saleem: data analysis and interpretation; Nosheen: drafting of the manuscript. All authors approved the final version.