Indian Journal of Public Health

: 2018  |  Volume : 62  |  Issue : 2  |  Page : 111--116

A cohort study on risk factors for preterm births in rural Gujarat

Poonam Trivedi1, Deepak Saxena2, Tapasvi Puwar3, Shital Savaliya4, Parthasarathi Ganguly5,  
1 Senior Research Assistant, Indian Institute of Public Health, Gandhinagar, Gujarat, India
2 Additional Professor, Indian Institute of Public Health, Gandhinagar, Gujarat, India
3 Associate Professor, Indian Institute of Public Health, Gandhinagar, Gujarat, India
4 Former Research Assistant, Indian Institute of Public Health, Gandhinagar, Gujarat, India
5 Former Additional Professor, Indian Institute of Public Health, Gandhinagar, Gujarat, India

Correspondence Address:
Poonam Trivedi
Indian Institute of Public Health, Palaj Village, Lekawada Cross Road, Opp. Air Force Head Quarter Main Gate, Chiloda Road, Gandhinagar - 382 355, Gujarat


Background: Prematurity is one of the leading causes of neonatal and under-five mortalities globally and also in India. It is an important determinant of short- and long-term morbidities in infants and children. Unfortunately, risk factors of majority of preterm births (PTBs) remain unexplained which calls for appropriate action. There is a dearth of community-based research on PTB and its risk factors, especially in high burden countries like India. Objectives: The objective of the study was to explore different risk factors for PTB. Methods: A cohort of 1977 antenatal mothers was enrolled at household level by trained field investigators and was followed up in four districts of Gujarat, India, to document the outcome of pregnancy. Pretested and structured questionnaires were used to collect information. A hierarchical regression model was used to analyze the risk factors for PTB. Results: Proportion of PTB was 9% among the enrolled cohort. Risk factors which were found to be significant on applying the hierarchical model were periodontal disease, long sleep duration, and sex during any trimester. Conclusions: The study suggests an urgent need for strengthening of existing guidelines for effective, evidence-based, and culturally appropriate interventions for prevention of PTB. Maintenance of good oral hygiene should find a place in routine recommendations for pregnant women, and antenatal examinations should include screening for oral hygiene also.

How to cite this article:
Trivedi P, Saxena D, Puwar T, Savaliya S, Ganguly P. A cohort study on risk factors for preterm births in rural Gujarat.Indian J Public Health 2018;62:111-116

How to cite this URL:
Trivedi P, Saxena D, Puwar T, Savaliya S, Ganguly P. A cohort study on risk factors for preterm births in rural Gujarat. Indian J Public Health [serial online] 2018 [cited 2023 Apr 2 ];62:111-116
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The Sustainable Development Goal 3 target 3.2 is to end preventable deaths of newborns and under-five children by 2030.[1] There is visible progress in maternal and child survival; however, the rate of decline for mortality reduction remains insufficient to reach the set targets in time. Literature indicates that one of the important barriers to the progress has been the failure to reduce deaths in the neonatal period and prematurity is the single most important cause of neonatal mortality.[2]

Globally, prematurity is one of the leading causes of under-five deaths. More than 1 in 10 of the world's infants is born too early every year.[3] Almost 1 million children die each year due to complications of preterm birth (PTB).[1] It is also the most important determinant of short- and long-term morbidities in infants and children and can have serious long-term health consequences.[4] Moreover, the economic and social cost of PTB is high.

In the past few years, India has shown strong political will such as vital policy decisions to address major causes of newborn deaths, providing special attention to sick newborns, infants born too soon, and infants born too small. Unfortunately, despite all these efforts, India has the highest number of deaths due to PTBs accounting for 35% of neonatal deaths and ranks 36th globally.[1] Recently, there is a significant increase in institutional deliveries in India which has provided an opportunity to bring down the neonatal infections,[5] but deaths due to PTBs still remain a challenge to the neonatal survival. A number of risk factors for PTB have been identified including a prior history of PTBs, underweight mothers, obesity, diabetes, hypertension, smoking, infection, maternal age, genetics, multifetal pregnancy, and pregnancies spaced too closely. Still, little is known about the interplay of these factors and other environmental and social factors in the causation of PTBs [3] and in the majority of PTBs risk factors remain unexplained. There is also a dearth of community-based research on PTBs and its risk factors, especially in high-burden countries like India.

Defining risk factors for prediction of PTB is a reasonable goal not only for identifying pregnant women at risk for preterm delivery but also for initiation of risk-specific preventive interventions. Therefore, the present community-based study was conducted to identify possible risk factors for PTBs in selected districts of Gujarat, India.

 Materials and Methods

A community-based prospective cohort study was carried out from June 2012 to April 2014 in four randomly selected districts of Gujarat, namely, Patan, Anand, Junagadh, and Dahod. To have a better representation, as per District Level Household Survey-3 data, from each overlapping quartile of sociodemographic and socioeconomic parameters, one district was selected. From each selected district, using lottery method, two blocks were randomly selected from poor and high performing blocks based on Ante Natal Care (ANC) registration and delivery at health institutions. From each block, three Primary Health Centers (PHCs) were selected randomly, and from each selected PHC, three study units (villages) were further selected, for example, PHC head quarter village, randomly selected one subcenter head quarter village, and nearest village to the selected subcenter.

At a population size for finite population correction factor of 1,000,000 and hypothesized 23.3% frequency of outcome factor in the population as reported by a study done in representative population [6] [(P) 23.3%±5; confi dence limits as % of 100 (absolute ±%) is 5%,] sample size estimated was 1648, and assuming 20% drop out total sample size for the study was 1976. However, during actual survey, a total of 2154 antenatal mothers were enrolled during allotted time.

Pregnant women with ≥7 months of pregnancy during a designated 12 months of reference period and who were willing to participate were enrolled for the study. Data were collected using pretested structured questionnaire at different stages.

The study was conducted in three phases.

Phase I: Enrollment phase

During this phase, pregnant women residing in the study areas were enrolled at household level and interviewed by field investigators. A total of six field investigators from nursing/nutrition background were recruited for the study. They were trained for comprehensive oral checkup at Indian Institute of Public Health Gandhinagar (IIPHG). The training was facilitated by trained dental health professionals. A comprehensive module on how to collect data was prepared by a group of experts from the field of epidemiology, obstetrics, dental surgery, and nursing to ensure the quality of data and to avoid interobserver variation.

Lists of pregnant females in the selected villages were obtained from the Auxiliary Nurse Midwives (ANM)/female health workers/Accredited Social Health Activists (ASHAs) in their respective areas of operation. Further to identify any missed out pregnancy in the list, snowball technique was adopted where all pregnant females enrolled in the study were inquired if they knew about any other pregnant woman in their locality to ensure all the pregnant women are listed.

Information on sociodemographic characteristics, present and past obstetric history, history of any illness, and health education received from health department regarding the risk of complications during pregnancy and knowledge about existing maternal health programs were captured. In addition, contact information of mother/household member and contact details of ANM/ASHA of respective villages were also obtained. After enrollment, females were tracked by monthly telephone calls made by field investigators and two follow-up home visits were done by field investigators to capture outcome of pregnancy.

Phase II: Follow-up

Field investigators provided two follow-up visits: 1st follow-up visit was done after 7 ± 1 days of delivery to document the birth outcome, gestational age at birth, type of delivery as well as their postnatal and survival status. A second follow-up visit was done after completion of 42 days to capture adverse pregnancy outcome, status of breastfeeding, health status of the infant, age-specific immunization, and complications, if any, during the puerperium period.

Definition of outcome variables

The study adopted the standard definition of the WHO for PTB.[7] It was defined as all births before 37 completed weeks of gestation or fewer than 259 days since the 1st day of a woman's last menstrual period. Assessment of gestation period was based on the date of last menstrual period (as recorded in the case sheet/ANC card). Oral health status of study participants was assessed by inspection by trained field investigators to detect dental cavities and periodontal disease.[8] Periodontal disease was defined as a gum disease that causes irritation, redness, and swelling of the gums.

Data were analyzed using SPSS statistical package version 22, (IBM Corp, Armonk, NY). Univariate analysis with unadjusted odds ratio was calculated, and hierarchical regression model was used to analyze the risk factors for the occurrence of PTB. The level of significance was set at P < 0.05.

Ethical approval for the study was obtained from Internal Ethics Committee of IIPHG.


A total of 2154 pregnant women were enrolled, of which 1977 women were successfully traced after delivery (7 + 1 day postdelivery) by follow-up visits as shown in [Figure 1]. The lost to follow-up was 8.2%. The mean age of the study participants was 24.6 ± 2.5 years. About 15.7% mothers got married before 18 years of age, and about 9% had their first pregnancy before 18 years of age. Other characteristics are illustrated in [Table 1].{Figure 1}{Table 1}

Antenatal care and complications

The coverage of Iron and Folic Acid (IFA) was 96.3%, though only half of the mothers (54.9%) consumed >50 IFA tablets. Moreover, around 7% of the mothers had never consumed any IFA in spite of receiving it. None of the antenatal mothers received ≥100 IFA. Assessment of health status showed that around 3.85% of mothers had periodontal disease, whereas the proportion of hypertension and diabetes was low (<1%). Other ANC complications and predictors for PTBs are depicted in [Table 2].{Table 2}

Intranatal care of enrolled mothers

A total of 1977 pregnant women were successfully followed up to know the outcome of pregnancy. Due to multiple pregnancies in some women, a total of 2009 deliveries were documented. Out of 1977 females followed 180 (9%) delivered preterm Babiess and the proportion of preterm Babies out of total 2009 delivery outcomes was 8.9%.

As the overall aim of the present study was to undertake risk factor analysis for the PTBs, based on the available literature and the observations, a list of possible factors having an impact on pregnancy outcomes was documented among the studied population. [Table 3] shows the association between different sociodemographic factors and PTB. As shown in [Table 4], birth outcome, sleeping hours during antenatal period, gender of the infant, periodontal disease, and number of IFA consumed were significantly associated with PTBs (P < 0.05).{Table 3}{Table 4}

Multivariate regression

Important confounding factors such as age at pregnancy, caste, religion, occupation, literacy, and number of ANC visits were controlled. The factors which remain statistically significant after controlling confounding factors include periodontal disease, sexually activity in any trimester, and >8 h sleep during pregnancy.

The logistic analysis (final model) shows that odds of having PTB is 11.4 times more among females with periodontal disease ([odds ratio (OR) = 11.4] 95% confidence interval [CI] = 6.3–20.6) and it remains significant after controlling confounding factors (P = 0.00). The females having sexual activity during pregnancy are having three times higher risk of having PTB as compared to females not having sexual activity ([OR = 3.6] 95% CI = 1.5–8.4) and is significantly associated with PTB (P value-0.003). It was also observed that less sleep (≤8 h.) is a protective factor for PTB (P value-0.03). It was also found that females who did not consume IFA are having 1.6 times ([OR = 1.6] 95% CI = 0.9–2.6) higher odds of having PTB, compared to who consumed >50 IFA tablets; however, the effect was not statistically significant.


The present study shows that the proportion of PTB was 8.9% among the enrolled cohort. However, two studies from South India and North India reported the incidence of PTB as 23.3% and 5.8%, respectively.[6],[8] Previous studies found that lack of antenatal care, clinical anemia, maternal illnesses such as hypertension, and other antenatal complications such as placenta previa are risk factors for PTBs.[9],[10],[11] Whereas in the current cohort on applying the hierarchical model after controlling for other variables, it was found that the periodontal disease (OR = 11.4), sexual activity during pregnancy (OR = 3.6), and long sleep hours.(OR = 0.7) are important risk factors for mothers to have preterm delivery in the state of Gujarat.

Study findings indicate periodontal disease during pregnancy significantly increase the risk of PTB and literature confirms the possible correlation between the two; a meta-analysis on periodontal disease and risk of PTB and low birth weight support this finding.[12] However, on validating it with current national guidelines,[13] it was found that adequate rest and refraining from sexual activity in the first 6 weeks of postpartum period or longer if the perineal wounds have not healed by then been included in ANM guidelines, but importance of assessment of oral hygiene during pregnancy is still missing.

The present study identified that sexual activity during any trimester of pregnancy is independent risk factor for PTB; however, study conducted by Mill et al.[14] on effect of sexual intercourse on labor found that preterm delivery was not higher in those having intercourse during antenatal period than in those abstaining. Unfortunately, there is no substantial evidence available about safety of sexual activity in those women who are at risk of adverse pregnancy outcome,[15] which needs to be explored.

The present study found that less sleep (≤8 h) during pregnancy is a protective for PTB and long maternal sleep hours (>8 h) as a risk factor for PTB. However, a study conducted by Kajeepeta et al.[16] reported that short sleep duration (≤6 h), long sleep duration (≥9 h), and vital exhaustion were associated with increased odds of all subtypes of spontaneous PTBs. Our finding may differ from those of Kajeepeta et al.[16] for several reasons. In the present study, there may be underestimation of sleep duration as it was subjective, self-reported by mothers. The education of study participants was also low in the present study. Another reason for the inconsistent finding is that the study was conducted in a hospital setting, while the present study was conducted in community setting.

The main strength of the present study is the prospective study design conducted at the population level with a large sample size. One limitation of the study is a loss to follow-up of enrolled mothers due to migration to their paternal houses for delivery.

 Conclusions and Recommendation

The present study suggests an urgent need for strengthening of existing guidelines for effective, feasible, and culturally appropriate interventions for prevention of PTB, especially screening of oral hygiene, which is currently absent. It may include targeted interventions such as encouraging and counseling women to seek ANC including IFA, maintaining appropriate oral hygiene, adequate rest, and to refrain from sexual activities during pregnancy for at-risk mothers. Such interventions will have a significant role in improving the neonatal and infant health scenario of the country.


We wish to extend our gratitude to various program managers with Department of Women and Child Development and of Health and Family Welfare, Government of Gujarat, for their enthusiastic involvement in the project.

Financial support and sponsorship

The research has received funding from the Indian Council of Medical Research.

Conflicts of interest

There are no conflicts of interest.


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