Birth weight of a child is an important indicator for reproductive health and general status of the population. Low birth weight (LBW) is considered to be the single most predictor of infant mortality, especially of deaths within first month of life. Birth weight is an important determinant of perinatal, neonatal, and postnatal outcomes. LBW according to the WHO is birth weight of less than 2,500 g, the measurement being taken preferably within the first hour of life before significant postnatal weight loss has occurred. LBW babies are broadly of two ypes: first, those born before 37 weeks (preterm) and second, those who have intrauterine growth retardation (IUGR).

LBW infants represent a significant health problem worldwide. The first authoritative estimates of mean birth weight and prevalence of LBW were produced by the WHO in 1979 and updated in 1982. Over 20 million babies are born each year weighing less than 2,500 g worldwide, resulting in LBW of 15.5%; 95.6% of LBW babies are born in developing countries. In India, according to the National Family Health Survey-3 (NFHS-3), prevalence of LBW babies is 21.5%; the prevalence being slightly higher in rural areas (22.1%) than in urban areas (20%) and this almost remained static for last one decade. In India, 29% of infant mortality rate is associated with LBW. Birth weight of the baby is influenced by many factors such as maternal age, maternal education, maternal weight, gestational weight gain, gestational hemoglobin percentage, hypertension, maternal height, socioeconomic condition, birth interval, and inadequate antenatal (ANC) care.

LBW babies are more likely to die in infancy, and many also have irreversible cognitive impairments and increased risk of developing noncommunicable diseases later in adulthood. According to the fetal origin of disease hypoth- esis, also known as Barker’s hypothesis, undernutrition at critical stages in fetal growth can cause an increased risk of adult degenerative diseases of hypertension, diabetes mellitus, hyperlipidemia, and syndrome X.

The 34th World Health Assembly of the WHO adopted the goal of reducing the incidence of LBW to less than 10% as part of the global strategy of “Health for All” by the year 2000. Reduction of LBW incidence is one of the ma- jor goals of the “World fit for Children” plan adopted by the United Nations General Assembly in 2002. The mortality due to LBW can be reduced if the risk factors are detected and managed early. Hence, this study was carried out to find the maternal factors associated with LBW so that appropriate strat- egies can be formulated to tackle the problem.

This study was conducted in Kancheepuram district, Tamil Nadu, India. The estimated sample size for case–control study was 222 [95% confidence interval (95% CI), power 80%, cases to controls ratio of 1, exposure among controls 9.5%, odds ratio (OR) 3.09], which was calculated using the Epi Info software, version 2.3.1. Four primary health centers (PHCs) and one government hospital (GH) from three blocks of Kancheepuram district, Tamil Nadu, providing obstetric care were approached, and data regarding birth weight of babies born between January 1, 2012 and December 31, 2012 were collected. The total number of deliveries in the selected PHCs and GH was 1537; of which, 208 were LBW babies. Cases and controls were selected on the basis of birth weight of the babies. Mothers who delivered babies with birth weight less than 2.5 kg, by any mode of de- livery, were selected as cases, and the consecutive mothers who delivered babies with birth weight more than or equal to 2.5 kg, by any mode of delivery, were selected as con- trols. The details of all LBW babies born during January 1, 2012 and December 31,2012 andtheircontrols were noted down.

The details of the mothers were collected from the registers, which included address, phone number, hemoglobin of the mother, history of pregnancy-induced hypertension (PIH) and gestational diabetes mellitus. The registers had incomplete address for many mothers.

Among them, mobile numbers were available for few mothers who were contacted and their locations were found. For those mothers who could not be contacted on mobile phone also, the Anganwadi worker in that particular area was contacted to get the information and few mothers were traced in this manner. Mothers who could not be traced (37 cases and 24 controls) and who were unavailable in their houses (9 cases and 14 controls) in spite of two visits, and mothers who were not residents of Kancheepuram district 23 cases and 31 controls) were excluded from the study.

Interview of the selected participants was held with a pretested and predesigned questionnaire by means of house visits to assess the sociodemographic factors and maternal characteristics that are associated with LBW. The sociode- mographic variables included the age of the mother, religion, caste, mother’s education and occupation, per capita income of the family, housing condition, place of cooking, and fuel used for cooking.

The maternal factors included age at child birth; parity; spacing between children; ANC, intranatal, and postnatal events; and maternal anthropometry. The study was carried out till the estimated sample size was achieved. The study was approved by the ethical review committee of the institute. Participant information sheet was given to the participants and written informed consent was obtained from each participant before data collection.

Data were entered in Microsoft Excel 2013 and were analyzed using SPSS software, version 16. OR and CI were calculated, and p-value of <0.05 was considered to be statistically significant. Multiple logistic regression analysis was done to adjust for confounders.