Gestational weight gain and term intrauterine growth restriction: a hospital based prospective cohort study
Date of Award
Master of Science in Epidemiology & Biostatistics (MSc Epidemiology & Biostats)
Community Health Sciences
Introduction: IUGR is a public health problem faced in developing countries where the burden is very high and associated with many short and long term consequences of neonatal morbidity and mortality .Maternal nutritional factors especially GWG has been thought to play a key role in IUGR in our setting but the exact contribution of nutritional factors to IUGR is not known. Objectives: To assess if low maternal gestational weight gain is a risk factor for an IUGR baby and to assess the relative proportion of term IUGR that is attributable to maternal malnutrition. Methodology: The study is a multi-center hospital based prospective cohort that was carried out in 3 hospitals of Karachi. In the current project, exposure variable that is total gestational weight gain is measured at two points to find the weight change.The outcome was term IUGR neonates who are diagnosed at the time of birth as falling below the 10th centile of weight for gestational ageon the Fenton chart and outcome are normal weight full term babies. The enrollment, data collection and follow up to delivery was done in 2 months. Patients were recruited at 37 weeks or more and followed to delivery. The sampling strategy employed was purposive sampling. Data collection tools employed were an in-depth questionnaire and anthropometrics of the mother and neonate.Descriptives were computed by T test and Chi square. A uni-variate analysis was done using Cox regression model and crude and weight gain-adjusted HR were reported. Then a Multivariable model was run using Cox regression to find the risk factors of IUGR.Lastly Levine's formula was used to calculate the Population Attributable Risks of IUGR in our setting. Results:Overall 358 mother-newborn dyads were obtained. The overall incidence of IUGR using predefined criteria of gestational age adjusted birth weight by the Fenton chart was 25.4 %.Effect modification is present between pre-pregnant BMI and gestational weight gain, at a lower BMI less weight gain has more risk of an UGR baby whereas at a higher BMI less weight gain is actually protective of IUGR.At BMI level <18.5,the risk of having IUGR is 1.43(0.24-7.66) times for those who had gestational weight gain of less than 7kg as compared to those who had gestational weight gain of more than 7kg throughout the study period ,controlling for all other variables whereas at BMI level >30,the risk of having IUGR is 0.81 times(0.14-4.16).71% of risk factors attributing to IUGR were explained by the study out of which 43% were maternal nutritional factors(pre pregnancy BMI, Gestational weight gain and Iron deficiency.) Conclusion: The evidence from this study reinforces the relationship of inadequate GWG and more importantly low pre-pregnancy nutritional status and IUGR. In a developing country nutritional factors contribute to around one half of IUGR burden. There are still a quarter of proportion of unknown factors that need to be paid attention to eliminate the burden of IUGR from a developing country.
Javed, W. (2011). Gestational weight gain and term intrauterine growth restriction: a hospital based prospective cohort study (Unpublished doctoral thesis). Aga Khan University, Karachi, Pakistan.