The prevalence of obesity in married women of age between 15-49 remained unchanged since the 2016 report, according to National Family Health Survey (NFHS)-5 (1) Women are also likely to retain gestational weight with each successive pregnancy. (2) Human pregnancy is an insulin resistant condition by itself. There is 40% to 50% increase in insulin resistance during pregnancy. (3) It is now universally acknowledged that maternal overweight and obesity are linked with adverse pregnancy outcome. Maternal complications include hypertension, DM, respiratory complications, thromboembolic disease. Newborn complications include congenital malformations, prematurity, large for gestational age infants, shoulder dystocia, macrosomia and long term adolescent complications like obesity and DM. (2,4,5) The effect of BMI on pregnancy and neonatal outcomes have been studied extensively and now it has been recognized that a high or low pre pregnancy body mass index (BMI) can adversely affect health outcomes of mother and child both in short-term and long-term. Obesity, GDM and excessive weight are thought to change the intrauterine environment and contribute to increased risk of obesity in children. Though routine weight checking of pregnant women has become an important feature of prenatal care, but little is known about effectiveness of weighing as a screening procedure for predicting adverse outcome. BMI is standard method used globally instead of weight to help quantify its effect. The World Health Organization has used this screening tool to classify people as underweight, normal and obese. (6) The present study was conducted to find the association of body mass index in pregnancy and its perinatal outcome in pregnant women and comparing the various factors between two groups.

A prospective clinical study was conducted at the OPD and IPD patients at the Department of Obstetrics and Gynaecology in Dr. D Y Patil Hospital & Research Institute, Kolhapur. All the necessary ethical permissions were taken from the Institutional Ethics Committee before starting the study. Duration period of the study was from October 2022—June 2023. Inclusion criteria- All pregnant women 18-weeks at first ANC irrespective of age and parity who were ready to be compliant for ANC visits and delivered at the study centre, pregnant women > 18weeks with well-maintained previous ANC records and those who were ready to give consent were included. Exclusion criteria- All pregnant women > 18weeks with no previous records, who were non- compliant, women with recent illness, infections during pregnancy like HIV, HBV syphilis, Twin pregnancy, Pre-existing Diabetes mellitus, Hypertension, Heart disease and those who refused to give consent were excluded. According to National Family Health Survey (NFHS-5,2019-20) prevalence of overweight women is 23.4%. (1) Sample size = (4PQ)/d2 = 4 × 23.4 × 76.6 / (4.5)2 = 354 Therefore, minimum sample size required was 354. 354 patients were taken into consideration for the study. At the time of registration, the baseline information was taken especially with respect to age, parity, weight & height. BMI was calculated for each patient according to formula (weight in kg)/ (height in meters)2 Baseline investigations like Hb, routine urine, VDRL, HIV tests carried out. Also gestational age was confirmed and congenital anomalies excluded by sonography. International classification of BMI used, which was also useful for comparison with other studies. Electronic digital weighing machine used for measurement of weight accuracy up to 200 grams. According to BMI, patients were classified into 4 groups. Body mass index <18.5kg/sqm---Under weight Body mass index 18.5kg/sqm-24.9kg/sqm---Normal weight Body mass index 25.0kg/sqm-29.9kg/sqm---Overweight Body mass index > 30.0kg/sqm---Obese At each visit, clinical data was recorded, weight measurement was carried out. USG & color Doppler study was done as per requirement. Antenatal complications if any, were noted & treated. Each and every patient was followed up till delivery. Prematurity, meconium aspiration and indication for NICU admission was noted. Statistical analysis done by using Chi-square test, ANOVA test. When P value was greater than 0.05 then the result was not statistically significant.

Table 1: Association between age and BMI in study groups Age (Years) BMI Total <18.5 18.5-24.99 25-29.99 30 & above <20 1 (25) 0 10 (4.81) 2 (2.06) 13 ( 365) 20 – 24 2 (50) 20 (42.55) 79 (37.98) 39 (40.21) 140 (39.33) 25 – 29 1 (25) 16 (34.04) 74 (35.58) 34 (35.05) 125 (35.11) 30 & above 0 11 (23.4) 45 (21.63) 22 (22.68) 78 (21.91) Total 4 (100) 47 ( 100) 208 (100) 97 (100) 356 (100) Chi-square = 9.60, P=0.38 Maximum percentage of cases are in 20-24-year age group which amounts to 39.33%, followed by 25-29-year age group which amounts for 35.11%. Least percentage of cases in <20yr age group. Samples are matched with P value 0.38 which is not statistically significant. Table 2: Association between mean gestational age and BMI in study groups BMI group N Mean GA Std. deviation A (<18.5) 4 32.785 5.35 B (18.5-22.9) 47 38.146 2.62 C (23-30) 208 38.801 1.27 D (>30) 97 38.512 1.36 ANOVA F=21.522, P=0.001 Mean gestational age for group A is 32. 78 which is lesser than remaining 3 groups for which it is 38 weak. Samples are matched with P value 0.001 which is statistically significant. Mode of delivery BMI Total Table 3: Association between mode of delivery and BMI in study groups <18.5 18.5 – 24.99 25 – 29.99 30 & above Vaginal 4 (100) 31 (65.96) 129 (62.02) 39 (40.21) 203 (57.02) Cesarean 0 15 (31.91) 77 (37.02) 56 (57.73) 148 (41.57) Instrumental 0 1 (2.13) 2 (0.96) 2 (2.06) 5 (1.40) Total 4 (100) 47 (100) 208 (100) 97 (100) 356 (100) Chi-square = 18.34, P=0.005 Percentage of vaginal delivery is 100% in group-A (underweight) and percentage of Cesarean is 57.73% in Group-D (obese) which is higher than other groups. Samples are matched with P value 0.005 which is statistically significant. Table 4: Association between details of indications of caesarean and BMI in study groups Indications of caesarean BMI Chi-square P Value <18.5 (n=4) 18.5 – 24.99 (n=47) 25 – 29.99 (n=208) 30 & above (n=97) Failed Induction 0 2 (4.25) 14 (6.73) 16 (16.49) 9.66, P=0.02 Previous CS 0 6 (12.17) 33 (15.87) 19 (19.59) 2.01, P=0.57 CPD 0 0 13 (6.25) 10 (10.31) 5.92, P=0.12 Fetal Distress 0 3 (6.38) 10 (4.81) 2 (2.06) 2.02, P=0.57 Breech 0 2 (4.25) 5 (2.4) 1 (1.03) 1.63, P=0.65 CDMR 0 2 (4.25) 2 (0.96) 3 (3.09) 3.08, P=0.38 PIH 0 0 0 5 (5.015) 13.54, P<0.0001 Cephalopelvic disproportion(CPD), Caesarean delivery on Maternal Request (CDMR), Pregnancy Induced Hypertension (PIH) Among various indications for caesarean most common was previous caesarean section with P value of 0.57 which is not statistically significant. Second most common indication was failed induction highest in Group-D with P value of 0.02 which is statistically significant. Another indication PIH was present in Group-D with P value of 0.0001 which is statistically significant. Table 5: Comparison of birth weight according to Body Mass Index in study group BMI Birth weight (Kgs) F Value P Value n Mean SD <18.5 4 2.05 1.072 14.16 <0.0001 18.5 – 24.99 47 2.80 .562 25 – 29.99 208 3.03 .396 30 & above 97 3.18 .455 With increasing BMI in different groups increase in mean birth weight is observed with highest mean birth weight of 3.18 kg in Group-D (obese) and least mean birth weight of 2.05 kg in group-A with P value of 0.0001 which is statistically significant. Also mean birth weight of study group was 2.77kg with SD of 0.62. Minimum birth weight was 0.6 kg and maximum 4.0 kg. Table 6: Association between low birth weight and BMI in study groups Birth weight (Kgs) BMI Total <18.5 18.5 – 24.99 25 – 29.99 30 & above <2.5 3 (75) 9 (19.15) 13 (6.25) 7 (7.22) 32 (8.99) 2.5 & above 1 (25) 38 (80.85) 195 (93.75) 90 (92.78) 324 (91.01) Total 4 (100) 47 (100) 208 (100) 97 (100) 356 (100) Chi-square = 29.52, P<0.0001 Highest percentage of low birth weight cases observed in group-A (75%) and least percentage of low birth weight cases observed in Group-D (7.22%) with P value of 0.0001 which is statistically significant. Maternal complications BMI Total <18.5 18.5 – 24.99 25 – 29.99 30 & above Present 0 7 (14.89) 49 (23.56) 45 (46.39) 101 (28.37) Absent 4 (100) 40 (85.11) 159 (76.44) 52 (53.61) 255 (71.63) Total 4 (100) 47 (100) 208 (100) 97 (100) 356 (100) Table 7: ociation between presence of maternal complications and BMI in study groups Chi-square = 23.66, P<0.0001 Maximum percentage (46.39%) of maternal complications are observed in Group-D (obese) and least percentage (0%) observed in group-A (underweight) with P value 0.0001 which is statistically significant. Table 8: Association between details of maternal complications and BMI in study groups Maternal complications BMI Chi-square P Value <18.5 (n=4) 18.5 – 24.99 (n=47) 25 – 29.99 (n=208) 30 & above (n=97) PIH 0 1 (2.13) 4 (1.92) 21 (21.65) 40.56, P<0.0001 GDM 0 2 (4.25) 26 (12.5) 16 (16.49) 4.95, P=0.18 Anemia 0 0 10 (4.81) 3 (3.09) 2.81, P=0.42 Perineal tear 0 3 (6.38) 8 (3.85) 6 (6.19) 1.29, P=0.73 PPH 0 1 (2.13) 2 (0.96) 4 (4.12) 3.52, P=0.32 SSI 0 0 1 (0.48) 5 (5.15) 9.74, P=0.02 Pregnancy Induced Hypertension (PIH), Gestational Diabetes Mellitus (GDM), Anaemia, Perineal Tear, Post – Partum Hemorrhage (PPH), Surgical Site Infection (SSI) Among maternal complications PIH (21.65%) and SSI (5.15%) were significantly high in Group-D (obese) with P value of 0.0001 and 0.2 respectively. Table 9: Association between presence of fetal complications and BMI in study groups Fetal complications BMI Total <18.5 18.5 – 24.99 25 – 29.99 30 & above Present 3 (75) 7 (14.89) 24 (11.54) 25 (25.77) 59 (16.57) Absent 1 (25) 40 (85.11) 184 (88.46) 72 (74.23) 297 (83.43) Total 4 (100) 47 (100) 208 (100) 97 (100) 356 (100) Chi square = 19.72, P<0.0001 It is observed that fetal complications are highest in (75%) in group-A (underweight) while 14.89%, 11.54% and 25.77% in group B, C and D respectively. Samples are matched with P value 0.0001 which is statistically significant. Table 10: Association between details of fetal complications and BMI in study groups Fetal complications BMI Chi-square P Value <18.5 (n=4) 18.5 – 24.99 (n=47) 25 – 29.99 (n=208) 30 & above (n=97) Prematurity 2 (50) 4 (8.51) 6 (2.88) 9 (9.28) 19.99, P<0.0001 Hypoglycemia 0 1 (2.13) 10 (4.81) 9 (9.28) 4.03, P=0.26 MAS 0 0 3 (1.44) 3 (3.09) 2.11, P=0.55 Hypothyroidism 0 0 2 (0.98) 0 1.43, P=0.70 IUD 1 (25) 1 (2.13) 0 1 (1.03) 30.67, P<0.0001 IUGR 0 1 (2.13) 2 (0.98) 0 1.82, P=0.61 Birth injury 0 0 1 (0.48) 3 (3.09) 4.74, P=0.19 Meconium Aspiration syndrome (MAS), Still Born Intra- Uterine Death (IUD), Intra Uterine Growth Restriction (IUGR) Among the fetal complications Prematurity (9.28%) and IUD (1.03%) are significantly high in Group-D (obese) with P value of 0.for both the groups.

In our study maximum percentage of population was in 20-24year group (39.33%) followed by 25-29-year group (35.11%). Only 3.65% of population was below 20 year of age, when matched with groups; the P value was 0.38 which was not statistically significant. Other studies have established relationship between increasing age and high BMI and obesity. Maximum percentage occurred in low BMI group-A (50%) while least percentage occurred in overweight BMI Group-C (2.88%) with P value of 0.001 which was statistically significant. This shows that incidence of preterm delivery decreases as BMI increases and thus, it statistically proves high association between low BMI and antenatal complication of preterm delivery. This observation is supported by a study done by Abram and Selvin which reported that low BMI associated with LBW and preterm delivery. (7) Most investigators report low pre-pregnancy weight as risk factor for preterm birth. Current evidence suggest that obesity may be associated with induced preterm delivery but not spontaneous preterm birth. “Maternal obesity is associated with an increased risk of medically indicated preterm birth and with a decrease in the risk of spontaneous preterm birth.” (8) Bhattacharya et al. also reported frequency of induced labour increases with increase in BMI, being lowest in underweight and highest in obese. (9) Smith et al. reported that among the nulliparous women the risk of spontaneous preterm delivery decreases with increase in BMI. (10) In our study there was more association of operative interventions in the form of LSCS and instrumental delivery in overweight (Group-C) and obese (Group-D). Overall LSCS rate in study group was 41.57%. Of all caesarean section 89.86% occurred in overweight BMI Group-C (52.03%) and obese BMI Group-D (37.84%) Most common indication LSCS was previous caesarean section amounting to 39.19% and second most common was failed induction amounting to 21.62%. Weiss and colleagues reported rate of CS among nulliparous women with normal BMI to be 20.7% and 33.8% for high BMI and 47.4% for obese patients. (11) Similar results were reported by Vahratian et al. (12) A study by Dietz et al. showed that incidence of CS increases with increases in pre-pregnancy BMI from 14.3% for low BMI to 42.6% for morbid obese women. (13) All these studies correlate with our study of association of high BMI and increases rate of CS with P value of 0.001 which was statistically significant. In our study, we found that 8.99% of cases have birth weight less than 2.5kg, 32.86% of cases have birth weight between 2.5-3kg and 41.57% cases have birth weight between 3-3.5kg of which is 62.16% belonging to Group-C and 25.58% belonged to Group-D. 14.89% babies have birth weight between 3.5-4kg of which 47.17% cases belong to Group-C and Group-D each. There were only 6 cases of more than 4kg which belong to overweight Group-C (33.33%) and obese Group-D (66.67%) with P value of 0.0001 which was statistically significant. In a study by Jensen et al. after excluding all the women with GDM, they concluded that risk of macrosomia was significantly more in obese and overweight women compared with normal BMI women. (14) The percentage of LBW was more in low BMI Group-A (underweight) amounting up to 75%. Incidence of LBW was 19.15%,6.25% and 7.22% in group B (normal), Group-C (overweight) and Group-D (obese) respectively with P value of 0.0001 which was statistically significant. A study done by Adam and Babikar et al. showed that maternal low BMI was significantly associated with LBW (OR=1.8, 95% CI= 1.0-3.2, P=0.02) and perinatal mortality (OR=6.5, 95% CI= 2.9-14.8, P<0.001). (15) Our study statistically proves high association of obesity and high BMI and gestational hypertension. Incidence of gestational hypertension in our study group was 5.9%. No cases occurred in group-A (underweight), 3.85% cases occurred in Group-B (normal weight) while maximum cases occurred in Group-D (obese) amounting to 80.78% with P value of 0.0001 which was statistically significant. A study done by Sattar et al. concluded that risk of gestational hypertension in pregnancy is three fold greater in obese women. (16) Study carried out by Kumari et al. reported that BMI more than 40 was associated with gestational hypertension in 28.8% cases compared with 2.9% in non- obese cases. (17) In a study done by Bianco et al. found that there was four fold increased risk of pre-eclampsia in obese women. (18) All above studies are correlating with our study in association of high BMI and obesity in pregnancy with development of gestational hypertension. In present study risk of GDM increased with increase in BMI, with incidence of 4.25%, 12.5% and 16.49% in Group-B (normal weight), Group-C (overweight) and Group-D (obese) respectively with P value of 0.18, which was not statistically significant. In a study Susan et al. estimated that “risk of developing GDM was about two, four and eight times higher in overweight, obese and severely obese women respectively.” (19) The incidence of anemia in our study group was 3.65% only. Of these maximum number of cases were seen in Group-C (overweight) which is 76.92% with P value of 0.42 which was not statistically significant. There was no study available to discuss relation of anemia in overweight and obese women in antenatal period. In present study incidence of IUGR was more in normal weight women (2.13%), followed by overweight women (0.98%) and no IUGR cases occurred in underweight and obese women with P value of 0.61, which was not statistically significant. Risk of PPH was more in group –D (obese) 4.12% compared to other groups with P value of 0.32 which was not statistically significant. In a cohort study of 11,14,071 women with singleton pregnancy who delivered in Sweden 1997 to 2008, it was found that risk of atonic uterine hemorrhage increases rapidly with increasing BMI and risk of uterine hemorrhage was twice in obese group (1.8%) compared with normal weight group (0.9%). Maximum percentage of fetal complications were seen in group-A (underweight) which was 75% while rest of the cases were distributed as 14.89%, 11.54% and 25.77% in Group-B (normal weight), Group-C (overweight) and Group-D (obese) respectively with P value of 0.0001 which was statistically significant. Most common complication was prematurity which accounted to 35.6%. Other complications were hypoglycemia and meconium aspiration syndrome, when compared in groups P value was 0.26 and 0.55 which was not statistically significant. A very severe complication, IUD (intra-uterine death) occurred in three cases. One case each occurred in underweight, normal weight and obese group but when compared with sample size in each group; underweight group-A have the maximum percentage amounting to 25% with P value of 0.0001 which was statistically significant. This result is supported by a study done by Stotland et al. which reported that low BMI was associated with more number of fetal complications like prematurity and respiratory distress syndrome. (20) Other complications like hypothyroidism, hypoglycemia and birth injury to baby with P value of 0.70, 0.26 and 0.19 respectively were not statistically significant. Surgical site infection was highest in Group-D amounting to 5.15% and least in Group-C amounting to 0.48% and absent in Group-A and Group-B with P value of 0.02 which was statistically significant. Other maternal complications like Pyrexia and Perineal tear were not statistically significant. Overall maternal complications were more in overweight and obese women while fetal complications were more in underweight.

In present study there is increased risk of low birth weight, anaemia, gestational hypertension, preterm delivery, induction of labor, caesarean section, postpartum hemorrhage and surgical site infection in abnormal BMI patients. Overall maternal complications were more in overweight and obese women while fetal complications were more in underweight. Hence, from the above study we can conclude that BMI in pregnancy has a great impact in both maternal and fetal outcome of pregnancy.

1. National Family Health Survey (NHFS-5), 2019-20. Adult Nutrition, India. 2. Yariv Yogev, Catalano P women and obesity. Pregnancy and obesity June 2009, volume 36 number-2, 285-300. 3. Schieve LA, Cogswell ME, maternal weight gain and preterm delivery. Differential effects of BMI. Epidemiology 1999;10;14-7. 4. Haugen M, Brantsaeter AL, Winkvist A, Lissner L, Alexander J Et al. Associations of pre-pregnancy body mass index and gestational weight gain with pregnancy outcome and postpartum weight retention: a prospective observational cohort study. BMC pregnancy childbirth. 2014; 14: 201. 5. Liu L, Hong Z, Zhang L. Associations of pre-pregnancy body mass index and gestational weight gain with pregnancy outcome in nulliparous women delivering single live babies. Scientific report. 2015; 5:12863. 6. World Health Organization. Global Database on Body Mass Index: BMI Classification. 7. Abrams and Selvin: Maternal Weight Gain Patterns, ACOG, Vol. 86, No.2, August 1995 8. Kanadys WM, Leszczynska- Gorzelak B, Jedrych M, Oleszczuk J. [Maternal pre-pregnancy obesity and the risk of preterm birth: a systematic overview of cohort studies with meta-analysis]. Ginekol Pol. 2012;83(4):270–9. Epub 2012/06/21 9. Bhattacharya S Liston WA et al, Effect of BMI on Pregnancy outcomes in Nulliparous Women. BMC, Public Health 2007, 24 (7) :168. 10. Smith GCS, Shah I, et al Maternal Obesity in early pregnancy and the risk for spontaneous and elective preterm births, Am J Public Health 2007; 97 (1); 157-62. 11. Weiss JL, Malone FD. Obesity obstetric complications and caesarean delivery rate--a population-based screening study. Am J Obs. Gynecol. 2004 Apr; 190(4):1091-7. 12. Vahratian A, Zhang J, Troendle JF, et al. Maternal pre-pregnancy overweight and obesity and the pattern of labor progression in term nulliparous women. Obstet Gynecol. 2004;104: 943– 951 13. Deitz PM et al. population based assessment of the risk of primary caesarean delivery due to excess pre pregnancy weight in nulliparous women. Maternal and Child Health J 2005;93(3)237-44. 14. Jensen DM et al Pregnancy outcome and pre pregnancy BMI in glucose tolerant Danish women. Am J Obstet Gynecol 2003: 189:239-44. 15. Adam I, Babiker S, Mohammed AA, Salih MM, Prins MH, Zaki ZM: Low body mass index, anaemia and poor perinatal outcome in a rural hospital in eastern Sudan. Journal of Tropical Pediatrics 2007, 54(3):202–204. 10.1093/tropej/fmm110 16. Sattar Holmes et al, antenatal waist circumference and hypertension risk. Obstet Gynecol 2001;97: 268-71. 17. Kumara A Pregnancy in morbid obesity Inte J Gynecol Obstet 2001; 73: 101-7. 18. Bianco AT et al. pregnancy outcome and weight gain recommendations for morbidly obese women. Obstet Gynecol 1998; 91:97-102. 19. Chu SY, Callaghan WM. Maternal Obesity and Risk of Gestational Diabetes Mellitus. Diabetes Care. 2007 August; 30(8): 2070-2076 20. Stotland et.al: Gestational weight gain and adverse neonatal outcome among term infants, ACOG Vol 108, No. 3, part 1, Sept 2006.