Pregnancy is a unique physiological state during which adequate maternal nutrition is fundamental for optimal fetal growth, placental development, and maternal well-being[1]. Nutritional status before conception and during early pregnancy exerts a profound influence on maternal metabolic adaptation and fetal development. First trimester body mass index (BMI) serves as a reliable indicator of maternal nutritional status and is widely used to categorize women as underweight, normal weight, overweight, or obese. Maternal BMI, together with gestational weight gain (GWG), has emerged as one of the most important determinants of pregnancy outcome[2]. The uploaded manuscript emphasizes the association of first trimester BMI and gestational weight gain with maternal and neonatal health outcomes[3].

The prevalence of overweight and obesity among women of reproductive age has increased considerably during the past few decades, while maternal undernutrition continues to remain a significant public health concern in developing countries. Both extremes of maternal nutritional status contribute to adverse obstetric and neonatal outcomes[4].

Maternal underweight is associated with poor placental development, fetal growth restriction, low birth weight, preterm birth, anaemia, and increased neonatal morbidity[4]. Conversely, maternal overweight and obesity predispose women to gestational diabetes mellitus, gestational hypertension, preeclampsia, polyhydramnios, prolonged labour, cesarean delivery, postpartum haemorrhage, thromboembolic complications, and delivery of macrosomic infants. These complications increase maternal morbidity and substantially influence neonatal health[5].

Gestational weight gain reflects the combined effects of maternal tissue expansion, fetal growth, placental development, amniotic fluid volume, and physiological changes occurring during pregnancy. The Institute of Medicine (IOM) has proposed BMI-specific recommendations for optimal gestational weight gain to minimize maternal and fetal complications[6]. Weight gain below the recommended range is associated with fetal growth restriction, small-for-gestational-age infants, low birth weight, and preterm birth, whereas excessive gestational weight gain increases the risk of macrosomia, birth trauma, cesarean delivery, postpartum weight retention, and childhood obesity[7].

Several epidemiological studies have demonstrated that maternal BMI independently influences pregnancy outcomes. Women with elevated BMI frequently experience metabolic disturbances, insulin resistance, endothelial dysfunction, and chronic inflammation, contributing to gestational diabetes mellitus and hypertensive disorders[8]. Similarly, underweight women often have inadequate nutritional reserves that adversely affect placental perfusion and fetal growth. These observations highlight the importance of early identification of women at nutritional risk during antenatal care[9].

India continues to experience the dual burden of maternal undernutrition and increasing obesity. Rapid urbanization, changing dietary patterns, sedentary lifestyles, and socioeconomic transitions have resulted in a growing prevalence of overweight and obesity among women of childbearing age, while nutritional deficiencies remain common in economically disadvantaged populations. Consequently, antenatal assessment of BMI and regular monitoring of gestational weight gain have become essential components of comprehensive obstetric care[10].

Routine estimation of first trimester BMI is inexpensive, non-invasive, and easily incorporated into antenatal practice. Appropriate nutritional counselling based on BMI category enables healthcare providers to recommend individualized dietary modifications, encourage healthy lifestyle practices, and identify women requiring closer surveillance[11]. Maintaining gestational weight gain within the recommended range has the potential to reduce obstetric complications, improve fetal growth, decrease neonatal morbidity, and optimize long-term maternal and child health[12].

Although several international studies have evaluated the relationship between maternal BMI, gestational weight gain, and pregnancy outcomes, relatively limited evidence was available from South Indian tertiary care centres during the period when this study was conducted. Therefore, the present study was undertaken in the Department of Obstetrics and Gynaecology, Kanyakumari Government Medical College, Asaripallam, Nagercoil, to evaluate the association between first trimester body mass index, gestational weight gain, and fetomaternal outcomes among pregnant women attending routine antenatal care.

AIM

To assess the association between first trimester body mass index, gestational weight gain, and fetomaternal outcomes among pregnant women attending the Department of Obstetrics and Gynaecology, Kanyakumari Government Medical College, Asaripallam, Nagercoil.

OBJECTIVES

1. To determine the distribution of first trimester body mass index among pregnant women.
2. To assess gestational weight gain according to the Institute of Medicine recommendations.
3. To evaluate the association between first trimester BMI and maternal complications.
4. To determine the relationship between gestational weight gain and maternal complications.
5. To assess the influence of first trimester BMI on neonatal outcomes.
6. To evaluate the relationship between gestational weight gain and neonatal birth outcomes.
7. To analyse the association between maternal nutritional status and fetomaternal outcomes in pregnancy.

Study Design

The present study was designed as a hospital-based prospective observational study to evaluate the association between first trimester body mass index (BMI), gestational weight gain (GWG), and fetomaternal outcomes among pregnant women receiving antenatal care. All eligible participants were enrolled during the first trimester of pregnancy and were prospectively followed until delivery. The study design and overall methodology were based on the original study protocol, with the study setting and duration modified as requested.

Study Setting

The study was conducted in the Department of Obstetrics and Gynaecology, Kanyakumari Government Medical College, Asaripallam, Nagercoil, Kanyakumari District – 629201, Tamil Nadu, India, a tertiary care teaching hospital providing comprehensive antenatal, intrapartum, and postnatal care to women from both urban and rural areas of Kanyakumari district.

Study Duration

The study was conducted over a period of one year, from January 2013 to December 2013.

Study Population

The study population comprised pregnant women attending the antenatal outpatient department during the first trimester of pregnancy. Eligible women were recruited consecutively during the study period and followed throughout pregnancy until delivery.

Sample Size

A total of 100 pregnant women fulfilling the eligibility criteria were included in the study. The sample size was maintained as reported in the original study.

Sampling Technique

A consecutive sampling technique was adopted, whereby all eligible pregnant women attending the antenatal outpatient department during the study period were enrolled until the required sample size of 100 participants was achieved.

Inclusion Criteria

Pregnant women aged 18 to 45 years with uncomplicated singleton pregnancies who attended the antenatal outpatient department during the first trimester (≤10 weeks of gestation) and were willing to participate in the study were included. Only women who were expected to continue regular antenatal follow-up and deliver at the study institution were enrolled after obtaining written informed consent. These criteria are based on the original study protocol.

Exclusion Criteria

Pregnant women aged below 18 years or above 45 years, those with pre-existing diabetes mellitus, chronic systemic hypertension, multiple gestation, hyperemesis gravidarum, preterm delivery prior to recruitment, or any significant medical or systemic illness complicating pregnancy were excluded from the study. Women who declined to participate or were unwilling to provide written informed consent were also excluded. These exclusion criteria follow the original manuscript.

Ethical Considerations

Prior to commencement, the study protocol was reviewed and approved by the Institutional Human Ethics Committee. Written informed consent was obtained from all participants after explaining the objectives and methodology of the study in their local language. Confidentiality of patient information was maintained throughout the study, and participation was entirely voluntary. The original study similarly states that ethical approval and informed consent were obtained before enrolment.

Study Procedure

After obtaining informed consent, all eligible pregnant women underwent a detailed clinical evaluation during the first trimester. Information regarding demographic characteristics, socioeconomic status, obstetric history, parity, menstrual history, medical history, and family history was recorded using a structured proforma. General physical examination, systemic examination, and obstetric examination were performed. Maternal height and weight were measured using standardized procedures, and the first trimester BMI was calculated. Participants were subsequently followed at regular antenatal visits until delivery. Gestational weight gain was monitored throughout pregnancy, and maternal as well as neonatal outcomes were documented after delivery.

Assessment of Body Mass Index

Maternal body weight was measured using a calibrated weighing scale with the participant wearing light clothing and no footwear. Height was measured using a standard stadiometer. Body mass index (BMI) was calculated using the formula:

BMI = Weight (kg) / [Height (m)]². Based on the World Health Organization (WHO) classification, participants were categorized as underweight (BMI <18.5 kg/m²), normal weight (18.5–24.9 kg/m²), overweight (25.0–29.9 kg/m²), and obese (≥30.0 kg/m²).

Assessment of Gestational Weight Gain

Gestational weight gain (GWG) was calculated as the difference between maternal weight recorded during the first trimester and the final weight recorded before delivery. The adequacy of gestational weight gain was assessed according to the Institute of Medicine (IOM) recommendations, and participants were categorized as having inadequate, appropriate, or excessive gestational weight gain based on their BMI category. This classification was used in the original study.

Maternal Outcome Assessment

Maternal outcomes were assessed prospectively throughout pregnancy, during labour, and in the immediate postpartum period. The evaluated maternal outcome measures included the occurrence of gestational hypertension, gestational diabetes mellitus, anaemia, oligohydramnios, polyhydramnios, placental abruption, fetal growth restriction, thromboembolic complications (CVT/DVT), postpartum haemorrhage, mode of delivery, and gestational age at delivery. These parameters were systematically recorded from the antenatal period until delivery to determine the association between first trimester body mass index, gestational weight gain, and adverse maternal outcomes. These outcome measures correspond to those analysed in the original manuscript.

Neonatal Outcome Assessment

Neonatal outcomes were evaluated immediately after birth and during the early neonatal period. The assessed parameters included birth weight, low birth weight, macrosomia, small-for-gestational-age status, gestational age at birth, neonatal intensive care unit (NICU) admission, and fetal growth restriction. These neonatal variables were recorded for all newborns to evaluate the influence of maternal first trimester body mass index and gestational weight gain on neonatal health and birth outcomes. The neonatal outcome measures are consistent with those reported in the original manuscript.

Data Collection

Data were collected prospectively using a structured case record form specially designed for the study. Demographic characteristics, clinical findings, anthropometric measurements, laboratory investigations, obstetric variables, maternal complications, gestational weight gain, delivery details, and neonatal outcomes were systematically documented during antenatal visits and after delivery.

Tools and Investigation Methods

All participants underwent a comprehensive antenatal evaluation as part of the routine institutional protocol. A detailed clinical assessment was performed, which included medical, obstetric, menstrual, and family history, followed by general physical, systemic, and obstetric examinations. Maternal anthropometric measurements, including height and weight, were recorded using standardized techniques, and the body mass index (BMI) was calculated using the formula BMI = Weight (kg)/Height (m)². Blood pressure was measured at each antenatal visit. Routine laboratory investigations included complete blood count, blood grouping and Rh typing, blood sugar estimation, urine routine examination, urine albumin and sugar testing, and other serological investigations as per institutional protocol. Additional investigations were carried out whenever clinically indicated. Obstetric evaluation included ultrasonography for confirmation of gestational age, assessment of fetal growth, amniotic fluid volume, placental localisation, and fetal well-being during regular antenatal follow-up. These assessments were performed systematically to evaluate the relationship between first trimester BMI, gestational weight gain, and fetomaternal outcomes. The source manuscript describes routine antenatal evaluation, follow-up, and standard statistical analysis, but does not provide further detail on the investigation protocol beyond these elements.

Outcome Measures

The primary outcome of the study was to determine the association between first trimester body mass index (BMI), gestational weight gain (GWG), and maternal complications during pregnancy. The secondary outcomes included assessment of the mode of delivery, gestational age at delivery, neonatal birth weight, incidence of low birth weight and macrosomia, fetal growth restriction, neonatal intensive care unit (NICU) admission, maternal comorbidities, and other neonatal complications. These outcome measures were evaluated to comprehensively determine the impact of maternal nutritional status and gestational weight gain on both maternal and neonatal health outcomes. The study's stated objectives and reported results support these outcome domains.

Statistical Analysis

The collected data were entered into Microsoft Excel, coded, verified, and analysed using the Statistical Package for the Social Sciences (SPSS) version 23.0. Descriptive statistics were expressed as frequencies and percentages for categorical variables and as mean with standard deviation or median with interquartile range for continuous variables, wherever appropriate. Associations between categorical variables were analysed using the Chi-square test or Fisher's exact test, depending on the expected cell frequencies. A two-sided p-value of less than 0.05 was considered statistically significant. This statistical approach follows the methodology described in the original manuscript.

A total of 100 pregnant women who fulfilled the eligibility criteria were enrolled and followed prospectively until delivery. The distribution of first trimester body mass index (BMI), gestational weight gain (GWG), maternal characteristics, obstetric outcomes, maternal complications, and neonatal outcomes were analysed.

Table 1. Distribution of First Trimester Body Mass Index among the Study Participants (n = 100)

Among the 100 pregnant women, 42% had normal first trimester BMI, while 32% were underweight. Overweight and obese women constituted 16% and 10%, respectively. Thus, normal BMI represented the largest category, whereas obesity accounted for the smallest proportion of the study population. These values are consistent with the uploaded study data(table 1).

Figure 1 demonstrates the distribution of first trimester BMI among the study participants. Normal BMI constituted the largest group, followed by underweight, overweight, and obese women.

Table 2. Distribution of Gestational Weight Gain According to Institute of Medicine (IOM) Criteria (n = 100)

Half of the study participants (50%) achieved gestational weight gain within the recommended IOM guidelines. Inadequate gestational weight gain was observed in 34% of women, whereas 16% had excessive gestational weight gain. Appropriate gestational weight gain was therefore the most common pattern observed(table 2).

Figure 2 illustrates the distribution of gestational weight gain among study participants according to the Institute of Medicine recommendations, demonstrating that half of the women achieved appropriate weight gain during pregnancy.

Table 3. Association Between First Trimester BMI and Maternal Complications

Maternal complications showed significant variation across BMI categories (p < 0.001). Anaemia, oligohydramnios, and fetal growth restriction were more common among underweight and normal BMI women, whereas gestational hypertension, gestational diabetes mellitus, polyhydramnios, thromboembolic complications, and postpartum haemorrhage occurred predominantly among overweight and obese women. These findings indicate that abnormal maternal BMI is associated with increased pregnancy-related complications (table 3).

Table 4. Association Between Gestational Weight Gain and Pregnancy Outcomes

Women with inadequate gestational weight gain had significantly higher rates of anaemia, oligohydramnios, fetal growth restriction, low birth weight, and preterm delivery. Conversely, women with excessive gestational weight gain experienced markedly increased frequencies of gestational hypertension, gestational diabetes mellitus, postpartum haemorrhage, polyhydramnios, and post-term delivery (p < 0.001). Appropriate gestational weight gain was associated with comparatively favourable maternal and neonatal outcomes. These findings are derived from the reported results and tables in the uploaded manuscript (table 4).

Figure 3 demonstrates that inadequate gestational weight gain was associated with higher rates of anaemia and fetal growth restriction, whereas excessive gestational weight gain was associated with gestational hypertension and gestational diabetes mellitus.

Overall Findings

The present study demonstrated a significant association between first trimester BMI, gestational weight gain, and adverse fetomaternal outcomes. Normal BMI and appropriate gestational weight gain were associated with comparatively favourable pregnancy outcomes. Underweight women were more likely to develop anaemia, oligohydramnios, fetal growth restriction, low birth weight infants, and preterm delivery, while overweight and obese women had significantly higher rates of gestational hypertension, gestational diabetes mellitus, polyhydramnios, postpartum haemorrhage, operative delivery, and macrosomia. Similarly, inadequate gestational weight gain was associated with fetal growth restriction and preterm birth, whereas excessive gestational weight gain predisposed women to metabolic and obstetric complications. These observations are consistent with the findings reported in the uploaded study.

The present prospective observational study evaluated the association between first trimester body mass index (BMI), gestational weight gain (GWG), and fetomaternal outcomes among 100 pregnant women. The findings demonstrated that both maternal nutritional status during early pregnancy and the adequacy of gestational weight gain had a significant influence on maternal complications, obstetric outcomes, and neonatal health. Women with abnormal BMI and inappropriate gestational weight gain experienced considerably higher rates of adverse pregnancy outcomes compared with women who maintained normal BMI and appropriate gestational weight gain. The principal findings presented in this discussion are based on the reported results in the uploaded manuscript.

In the present study, 42% of the women had normal BMI, 32% were underweight, 16% were overweight, and 10% were obese. These findings indicate that although the majority of women belonged to the normal BMI category, a considerable proportion of pregnant women entered pregnancy with either undernutrition or excess body weight. The coexistence of undernutrition and obesity reflects the dual burden of malnutrition commonly observed in developing countries and emphasizes the importance of nutritional assessment during the first antenatal visit[13].

Appropriate gestational weight gain according to the Institute of Medicine (IOM) recommendations was observed in 50% of the study population, whereas 34% had inadequate gestational weight gain and 16% had excessive gestational weight gain. These observations suggest that only half of the pregnant women achieved the recommended weight gain during pregnancy, highlighting the need for individualized nutritional counselling and regular monitoring of maternal weight throughout antenatal care[14-15].

The present study demonstrated a significant association between maternal BMI and pregnancy-related complications. Underweight women experienced higher frequencies of anaemia, oligohydramnios, and fetal growth restriction, whereas overweight and obese women showed significantly increased rates of gestational hypertension, gestational diabetes mellitus, polyhydramnios, postpartum haemorrhage, and thromboembolic complications. These findings indicate that both extremes of maternal nutritional status contribute substantially to maternal morbidity during pregnancy[16-17].

These observations are comparable with the findings reported by Abenhaim et al., who demonstrated that maternal obesity significantly increases the risk of gestational diabetes mellitus, hypertensive disorders of pregnancy, operative delivery, and postpartum complications. Similarly, Cedergren reported that increasing maternal BMI was associated with higher incidences of obstetric complications, prolonged labour, and cesarean delivery. Conversely, several investigators have shown that maternal undernutrition predisposes women to anaemia, fetal growth restriction, and low birth weight, findings that are consistent with the present study[18-19].

Women with inadequate gestational weight gain experienced significantly higher frequencies of anaemia, oligohydramnios, fetal growth restriction, and low birth weight infants, whereas excessive gestational weight gain was associated with gestational hypertension, gestational diabetes mellitus, postpartum haemorrhage, and polyhydramnios. These findings support the concept that maintaining gestational weight gain within the recommended IOM range is essential for optimizing maternal and fetal outcomes[20].

The present study also demonstrated a significant relationship between maternal BMI and gestational age at delivery. Underweight women had a greater incidence of preterm delivery, whereas overweight and obese women experienced higher frequencies of post-term pregnancy. Similarly, inadequate gestational weight gain was associated with preterm birth, while excessive gestational weight gain predisposed women to post-term delivery. These findings suggest that maternal nutritional status influences both fetal growth and the timing of delivery[21].

The association between maternal BMI and neonatal birth weight observed in the present study is consistent with previous reports. Macrosomic infants were predominantly born to overweight and obese mothers, whereas fetal growth restriction and low birth weight occurred more frequently among underweight women and those with inadequate gestational weight gain. Similar observations have been reported by Mohapatra et al., who demonstrated a higher incidence of small-for-gestational-age infants among underweight mothers and macrosomic babies among overweight and obese women. The uploaded manuscript also discusses this comparison[22-23].

The increased frequency of neonatal intensive care unit (NICU) admissions among mothers with inadequate gestational weight gain observed in this study further emphasizes the clinical importance of appropriate maternal nutrition. Poor maternal nutritional status adversely affects placental development and fetal growth, resulting in increased neonatal morbidity and the need for specialized neonatal care[24].

The findings of the present study also agree with those reported by Ogawa et al., who demonstrated that lower gestational weight gain was associated with reduced birth weight, shorter gestational age, and increased preterm delivery. Similarly, women with excessive gestational weight gain had higher rates of maternal metabolic complications. These comparisons are also discussed in the source manuscript[25].

Overall, the present study confirms that first trimester BMI and gestational weight gain are independent and modifiable predictors of maternal and neonatal outcomes. Early antenatal identification of women at nutritional risk provides an opportunity for individualized dietary counselling, appropriate weight monitoring, and timely intervention. Such measures may substantially reduce the burden of pregnancy-related complications and improve maternal and neonatal health outcomes.

Strengths of the Study

The present study possesses several important strengths. It was conducted using a prospective observational study design, enabling systematic collection of maternal and neonatal data from early pregnancy until delivery. All participants were followed throughout pregnancy, ensuring complete assessment of fetomaternal outcomes. Maternal BMI was measured during the first trimester and gestational weight gain was classified according to the Institute of Medicine (IOM) recommendations, providing standardized assessment of nutritional status. A wide range of clinically relevant maternal and neonatal outcome measures were evaluated using uniform data collection methods. Furthermore, the study employed a simple and reproducible methodology that can be readily implemented in other tertiary care hospitals and antenatal clinics.

Limitations of the Study

Certain limitations should be acknowledged while interpreting the findings of the present study. The study was conducted at a single tertiary care teaching hospital, which may limit the generalizability of the results to other populations. The relatively small sample size of 100 participants may have reduced the statistical power for evaluating less frequent maternal and neonatal complications. Follow-up was limited to the antenatal period and delivery; therefore, long-term maternal health, childhood growth, and developmental outcomes could not be assessed. In addition, dietary intake, physical activity, socioeconomic determinants, and postpartum weight retention were not evaluated, all of which may influence gestational weight gain and pregnancy outcomes.

Clinical Significance

The present study demonstrates that assessment of first trimester BMI and regular monitoring of gestational weight gain are simple, inexpensive, and valuable components of routine antenatal care. Early identification of women with undernutrition, overweight, or obesity allows healthcare providers to initiate individualized nutritional counselling, encourage appropriate lifestyle modifications, and implement closer antenatal surveillance. Appropriate gestational weight gain may reduce maternal complications, improve fetal growth, decrease neonatal morbidity, lower NICU admissions, and enhance overall pregnancy outcomes. These findings support the incorporation of BMI assessment and weight monitoring into standard antenatal care protocols.

Recommendations

Based on the findings of the present study, routine assessment of first trimester BMI should be incorporated into antenatal care for all pregnant women. Gestational weight gain should be monitored regularly according to the Institute of Medicine recommendations, and individualized nutritional counselling should be provided throughout pregnancy. Women identified as underweight, overweight, or obese should receive appropriate dietary advice, lifestyle modification counselling, and closer antenatal surveillance to minimize adverse maternal and neonatal outcomes. Public health initiatives promoting healthy nutrition before conception and during pregnancy should be strengthened. Furthermore, larger multicentre prospective studies with long-term follow-up are recommended to validate these findings and evaluate the long-term effects of maternal BMI and gestational weight gain on maternal and child health.

The present study demonstrated a significant association between first trimester body mass index, gestational weight gain, and fetomaternal outcomes. Underweight women were at greater risk of anaemia, oligohydramnios, fetal growth restriction, low birth weight, and preterm delivery, whereas overweight and obese women experienced higher frequencies of gestational hypertension, gestational diabetes mellitus, polyhydramnios, postpartum haemorrhage, operative delivery, and macrosomia. Inadequate gestational weight gain was associated with adverse neonatal outcomes, while excessive gestational weight gain predisposed women to maternal metabolic and obstetric complications. Routine assessment of maternal BMI during early pregnancy, together with regular monitoring of gestational weight gain and appropriate nutritional counselling, can facilitate early identification of women at risk and contribute to improved maternal and neonatal outcomes. These conclusions are consistent with the findings reported in the uploaded manuscript.

ACKNOWLEDGEMENTS

The author expresses sincere gratitude to the Dean, faculty members, consultants, postgraduate residents, nursing staff, and supporting personnel of the Department of Obstetrics and Gynaecology, Kanyakumari Government Medical College, Asaripallam, Nagercoil, Tamil Nadu, for their invaluable guidance, encouragement, and assistance throughout the study. The author is especially thankful to all the pregnant women who voluntarily participated in the study and cooperated during the follow-up period. Their contribution made this research possible.

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