Effect of body mass index on pregnancy outcome at Kenyatta National Hospital: Cohort Study
View/ Open
Date
2012Author
Ritho, Milka Muthoni K
Type
ThesisLanguage
en_USMetadata
Show full item recordAbstract
The increasing population of overweight and obese women world-wide is a major public health concern now reaching epidemic proportions. Two thirds of these women are in the reproductive age which has critical consequences for fetal and maternal health. Maternal obesity has been shown to be associated with adverse pregnancy outcomes such as hypertension, diabetes, infections such a urinary tract infections (UTI), preterm labor, increased cesarean delivery; and poor neonatal outcomes such RDS, macrosomia and prematurity. Obesity thus results in increased maternal and perinatal morbidity and mortality with increased costs of
provision of healthcare.
Objective
This study was aimed at determining the effect of high maternal body mass index (BM!) i.e. 2: 25 and gestational weight gain on pregnancy outcomes.
Study setting
The study was carried out at the K.N.H labour ward
Study design
This study was designed as a hospital based cohort study
Study population
This was comprised of mothers coming to K.N.H for delivery. A total of 400 women were recruited into the study, the exposed group were women with increased BMI i.e. >25 and the unexposed were women with normal BM! i.e. 18.5-24.9.The exposed were 226 in total and were further divided into overweight group (BMI 25-29.9) with 203 women and obese group (BMI 30-34.9) with 23 women. The unexposed were 174 in number.
Study Methodology
The women delivering at the KNH labor ward were randomly rec~i~ed in the first stage of labor after their booking BMI at or before 20 weeks gestation was calculated from the antenatal cards. BMI was established by use of measures of height and weight using the formula BMI= weight (kg) -:--height (m) 2. The maternal outcomes of interest were pregnancy induced hypertension, pre- eclampsia, eclampsia, gestational diabetes, PROM, preterm delivery, post term delivery,
induction of labor and its indications, caesarian section and its indication, postpartum hemorrhage and duration of hospital stay. Fetal outcomes of interest include SGA, LGA, RDS and perinatal deaths. The frequency of these outcomes in each BMI group was recorded and compared using univariate and multivariate regression techniques which controlled for confounding factors.
Data Handling and analysis:
The extracted data was entered into Statistical Package of Social Scienceル (SPSS) version 17.0 for Windows (SPSS, Chicago, IL, USA) statistical software to check for errors and perform the requisite statistical test. Frequency distribution was used for data cleaning. Data was analyzed using the same software. Descriptive analysis was performed to characterize the number and type of patient outcome. To obtain insight into the social demographics factors of the patients,
frequency tables were used with accompanying percentages. Bivariate comparison of continuous symmetric characteristic was performed using t-test and using the Mann-Whitney test for non- symmetric characteristics. Fisher exact test and chi square test, as appropriate was used for comparison of categorical characteristics.
Correlation between variables was tested using the Pearson correlation co-efficient. Statistical significance was defined as a two tailed p-value ofless than or equal to 0.05.
Results
In comparison with women ofBMI 20 - 24.9, obese women faced the highest risk of pre- eclampsia OR 2.368 (95% CI 1.190,4.700), pregnancy induced hypertension OR 4.320(95% C.I 1.200, 15.910, induced labour OR 4.300 (95% CI 1.390, 13.310), emergency Caesarean section rates OR 2.35 (95% CI 0.896, 6.817) and post term delivery ORl.346 (95% CI 0.499-3.633). Overweight women were more likely to have eclampsia OR 3.17 (95% CI 1.02,9.80) and still
births OR 3.170 (95% CI 1.020, 9.800) . The highest risk of birth weights> 4,000 g was in obese OR4.327 (95% CI 1.123, 16.672). Majority ofthe women in the normal BMI group had inadequate weight gain in pregnancy (81.6%) while majority ofthose in the overweight (84.72) and obese (73.91) groups had recommended weight gain. There was no positive linear association between excessive gestational weight gain and obstetric outcomes. Inadequate gestational weight gain was associated with increased risk ofRDS OR 1.985 (p =0.016), SGA OR 1.1365 (p=0.Ol7) and preterm labour OR 1.88 (p=O.051).
Conclusion
This study showed that increased maternal BMI is associated with increased risk of adverse obstetric outcomes and increased intervention rates. These include increased risk of PIH, pre- eclampsia, fetal macrosomia, post term pregnancy, induction of labour , ceaserian delivery and still births. Excessive gestational weight gain did not result in increased risk of adverse outcomes; however, inadequate weight gain was associated with increased risk of preterm labour and SGA
Recommendations
Preconception nutritional counseling is important for management of obesity before pregnancy. Inappropriate weight gain in pregnancy (inadequate or excessive) should be recognized early enough and acted upon to reduce the attendant complications. A nationwide community-based prospective study should be done to provide in-depth knowledge about the prevalence and impact of different categories ofBMI on pregnancy outcomes among different socioeconomic and ethnic groups. Policy makers need to recognize increased BMI as a health issue is prevalent in our population and formulate guidelines on management of these women to optimize maternal and fetal outcome
Publisher
University of Nairobi, Kenya