**1. Introduction**

The perinatal mortality rate, which is one of the important adverse pregnancy outcome and includes stillbirths and infant death within first week of life is estimated to be nearly 40 deaths per 1,000 pregnancies in Gujarat. Also the infant mortality rates have been estimated to be 50 deaths before age of one year per 1,000 pregnancies. It is stated that children whose mothers are illiterate or belong to low socio-economic class have two and half times more chances to die within 1 year of their birth compared to those whose mothers have completed atleast 10 years of education or belong to high socio-economic class. There are nearly 13% of women who does not receive proper antenatal care and facility during pregnancy [1].

In India, there are nearly half of the women (52%) who possess normal BMI range: rest are either underweight or overweight. Approximately 55% of the women of total population in India are anaemic. These maternal parameters directly affect the children causing 48% of the children to be malnourished and 43% to be underweight [2].

The impact of prepregnancy body mass index (BMI) on maternal as well as neonatal outcomes has attracted wide spread attention these days. Several of the recent studies had reported that the prepregnancy BMI is associated with the child birth weight and it is also reported that mothers' whose weight gain during pregnancy may be excessive or inadequate are more prone to poor maternal and child outcomes. The range of weight gain during pregnancy is constant since last 10 years, although it may differs from one to another according to the maternal BMI [3]. According to the recommendations for weight gain during pregnancy by Institute of Medicine (IOM), both prepregnancy BMI and GWG are associated with the outcomes of pregnancy, either in correlation to mother or neonate or in both. Maternal and neonatal complications associated with BMI and GWG are of public health importance because they add to the disease burden in women and children and also increase the medical costs. Prior to pregnancy, all women should strive for appropriate body weights [4]. Gestational weight gain is a modifiable factor which can be controlled through diet as well as nutritional counselling during pregnancy to modify the inadequate or excessive weight [5].

The antenatal care involves various actions such as prevention and health care promotion of mother as well as neonate, early diagnosis and appropriate treatment of any problem occurring during this period of time. For proper antenatal care, monitoring the nutritional intake and status of pregnant women is important along

#### *Association of Pre-Pregnancy Body Mass Index and Gestational Weight Gain with Preterm… DOI: http://dx.doi.org/10.5772/intechopen.96922*

with examining the gestational weight gain, haemoglobin level which also possesses direct co-relation with maternal and foetal health [6].

Various studies have been conducted which suggests the correlation of different maternal parameters with adverse pregnancy outcomes. A study by Li et al. observed that maternal prepregnancy BMI was positively associated with risks of gestational diabetes mellitus (GDM), pregnancy-induced hypertension, caesarean delivery, preterm delivery, LGA, and macrosomia, and inversely associated with risks of SGA and LBW. They also found that maternal excessive GWG was associated with increased risks of pregnancy-induced hypertension, caesarean delivery, LGA, and macrosomia, and decreased risks of preterm delivery, SGA, and low birth weight [3]. Another study by Steer P.J observed that the minimum incidence of low birth weight (< 2.5 kg) and preterm labor (< 37 completed weeks) occurs in association with a haemoglobin concentration of 95–105 g/L. Thus associating the haemoglobin levels with infant birth weight and term of delivery [7]. Adverse pregnancy outcomes are more common in women who begin the gestation as undernourished or as obese in comparison to pregnant women whose weight is within normal ranges. Maternal malnutrition increases the risks of birth weight, premature birth, foetal growth retardation, SGA infants and is associated with perinatal morbidity and mortality; insufficient intake of certain nutrients is related to some foetal congenital anomalies and birth defects. Gestational underweight has also been linked to infant inclination to certain chronic illnesses (diabetes mellitus type 2, hypertension, coronary disease, and stroke) in adulthood [8].

Low prepregnancy BMI (<19.5) is associated with many adverse pregnancy outcomes. In a country like India, where maternal underweight remains more common than overweight, the influence of maternal underweight BMI can affect mother and neonate adversely in many ways. Low Prepregnancy BMI is said to be associated with pregnancy outcomes such as preterm birth, LBW (i.e. birth weight less than 2500grams) or small SGA [9]. Women with lower than normal maternal body weight are prone to elevated risk for adverse prenatal outcomes such as intrauterine growth restriction (IUGR) as well as increased risk of subsequent obesity and hypertension in the offspring [10]. Also the SGA neonates are at risk for low Apgar scores, meconium aspiration, seizures, respiratory complications, extended hospital stays, and long-term squeal, including metabolic syndrome and neurologic deficits [11].

The prevalence of overweight (BMI 25–29.9 kg/m<sup>2</sup> ) and obesity (BMI 30–34.9 kg/m<sup>2</sup> ) is increasing rapidly among obstetric population. Further studies report that complications due to obesity can cause excess health care service use, including increased hospital stay during or after pregnancy [12]. Women with higher BMI during pregnancy are at higher risk of antenatal, intrapartum, postpartum and neonatal complications. Antenatal complications include recurrent miscarriage, congenital malformations, pregnancy induced hypertension (PIH), pre-eclampsia, gestational diabetes mellitus (GDM) and venous thromboembolism. Overweight and obese women are more likely to be induced and require a caesarean. Infants of overweight and obese mothers are often macrosomic and require prolonged hospital admission [13].

The iron concentration is less in females compared to males because of blood loss due to menstruation. Moreover during pregnancy, the foetal demand of iron is increased so more iron intake is required. It is also observed that the absorption of iron from the food during pregnancy increases along with the increasing gestational week, but this occurs only if there if sufficient iron concentration in the diet. Although very rare, but incidences of anaemia causing low birth weight and pre-term birth have been reported [7].

It is very important to maintain maternal nutritional status during pregnancy since it directly affects the foetal growth prior and post-delivery. It is highly recommended to consume balanced diet during pregnancy which is described by Indian Council of Medical Research (ICMR). It is frequently observed that low or improper nutrition intake during pregnancy may lead to insufficient weight gain, pre-term delivery, still birth, IUGR, as well as increase the morbidity and mortality rates which directly affect the maternal and neonatal health [14].

In modern times, the stress is increasing day by day. Since antiquity, people have thought that the emotions and experiences of a pregnant woman impinge on her developing foetus. Maternal stress has been found to possess adverse effect on perinatal as well as future developmental outcomes. Various stressors may be responsible for causing stress in pregnant women such as various life events (death of a relative, divorce, serious illness etc.), any physical aggravations, financial, domestic or any such type of factor. Any of the stressors thus activates the hypothalamus–pituitary– adrenal cortex system (HPA axis) and the sympathetic nervous system–adrenal medulla system. Hormonal imbalance occurs within the system because of hormones like Corticotropin Releasing Hormone (CRH), Adrenocorticotropin-releasing Hormone (ACTH), cortisol, and noradrenaline release. Spontaneous abortions, structural malfunction, preeclampsia, preterm delivery and low birth weight are the general adverse outcomes of various types of stress during pregnancy [15, 16].

According to the recent estimates of third National Family Health Survey (NFHS-3, 2005–2006), more than one-third (33%) of ever-married women aged 15 ± 49 in India have a BMI below 18.5 indicating chronic nutritional deficiency (CED) or underweight, and 14.8% of women are overweight or obese. Out of 29 Indian states, in total 13 states, more than 35% of women are too thin, and the percentage of overweight are more than underweight women in the states of Delhi, Punjab, Sikkim, Kerala, that is, a significant proportion of underweight women coexisting with high rates of overweight or obese in these states. Thus, Indian women suffer from a dual burden of malnutrition, with nearly half (48%) being either too thin or overweight. On the other hand, the percentage of thinness and overweight or obese is somewhat lower for men aged 15 ± 49 (34 and 9%, respectively) than for women aged 15 ± 49 [17].

As such pregnancy and its complications can occur in any part of the world without any correlation with race or species. Various studies are conducted in India which correlate individually between various aspects of GWG and maternal pre-pregnancy BMI to preterm delivery, but no such studies are conducted in the state of Gujarat regarding the same. Hence a study was designed to investigate the correlation between GWG, pre-pregnancy BMI, haemoglobin concentrations, various stressors and diet during the period of pregnancy, with the preterm delivery. The main aim and objectives of the study were to study prevalence of underweight, overweight or obese pregnant women and GWG during pregnancy, to determine the risk of underweight, overweight or obese pre-pregnancy BMI, and other comorbidities in pregnant women, to study the correlation between Pre-pregnancy BMI as well as GWG during pregnancy and preterm birth.

#### **2. Study methodology**

#### **2.1 Study design**

This was a prospective, multi-centric study which involved pregnant women from various hospitals whose detailed information was filled in the case record form. The study involved pregnant women with gestation week ≤20 weeks.

*Association of Pre-Pregnancy Body Mass Index and Gestational Weight Gain with Preterm… DOI: http://dx.doi.org/10.5772/intechopen.96922*

Informed consent of the pregnant women and the permission from hospitals were study was conducted was taken. Study approval was obtained from Institutional Ethical Committee, in agreement with local legal prescriptions, for formal review and approval of the study conduct. CRF and ICF were also submitted along with this for ethics committee approval. The study proposal was approved by Institutional Ethical Committee, Nirma University (Approval No: IEC/NU/14/2).

A pre-designed case record form was used for data collection. Information on maternal and paternal demographic data, socio-economic status, education and habit was taken. Also details regarding type of family, physical or mental stress, dietary information, history regarding gravidity and parity, present data regarding last menstrual date, estimated delivery date, comorbid conditions, actual delivery date, type of delivery, infant weight and gender was noted. Details of laboratory investigations, vitals, GWG and current medications were recorded from the file of pregnant women given from respective hospitals. Weight and height were measured by standard protocol and calibrated instruments. BMI was calculated as weight (kg) divided by height (m2 ).

Privacy and confidentiality of pregnant women was maintained at all levels and subject name, address or contacts was not revealed at any stage during the study.

## **2.2 Settings and location**

Pregnant women were selected randomly from Gujarat Cancer Society Medical College, Hospital and Research Centre, Binal Maternity Nursing Home and Nanavati Maternity Hospital.

#### **2.3 Sample size selection**

Sample size calculated was 384. The sample size calculation was done based on the prevalence of pre-term delivery in pregnant women in India. Out of 384 women, study was done on 250 women due to limited time availability. Amongst them, 226 women appeared for delivery at the same hospital from which they were enrolled. So finally the data of 226 were used for the study purpose.

#### **2.4 Sampling criteria**
