BACKGROUND: Gestational weight gain (GWG) is an important indicator of fetal well-being during pregnancy. Inadequate or excessive GWG could have undesirable effects on birth weight. However, information regarding the influence of GWG on birth weight is lacking from the Ethiopian setting. OBJECTIVE: This study aimed to determine the influence of GWG and other maternal-related factors on birth weight in Addis Ababa, Ethiopia. DESIGN AND METHODS: A cohort of pregnant women who received the first antenatal care before or at 16 weeks of gestation in health centres in Addis Ababa were followed from 10 January 2019 to 25 September 2019. Data were collected using a structured questionnaire and medical record reviews. We conducted a multivariable linear regression analysis to determine the independent effect of gestational weight on birth weight. RESULTS: Of the 395 women enrolled in the study, the participants’ pregnancy outcome was available for 329 (83.3%). The mean birth weight was 3130 (SD, 509) g. The proportion of low birth weight (<2500 g) was 7.5% (95% CI 4.8% to 11.0%). Babies born to underweight women were 150.9 g (95% CI 5.8 to 308.6 g, p=0.049) lighter than babies born to normal-weight women. Similarly, babies whose mothers gained inadequate weight were 248 g (95% CI 112.8 to 383.6 g, p<0.001) lighter than those who gained adequate weight. Moreover, babies whose mothers had a previous history of abortion or miscarriages or developed gestational hypertension in the current pregnancy were 147.2 g (95% CI 3.2 to 291.3 g, p=0.045) and 310.7 g (95% CI 62.7 to 552.8 g, p=0.012) lighter, respectively, compared with those whose mothers had not. CONCLUSIONS: Prepregnancy weight, GWG, having had a previous history of abortion or miscarriages, and developing gestational hypertension during a current pregnancy were independently associated with birth weight. Pregnancy-related weight management should be actively promoted through intensive counseling during routine antenatal care contacts.
This study was conducted in Addis Ababa, Ethiopia’s capital and the largest city. Participants were selected from nine health centres. The previously published paper reported details of the study setting and numbers of women recruited from each facility.31 A cohort of pregnant women were followed from before or at their 16 th week of gestation until they gave birth to assess their GWG and the baby’s birth weight from 10 January 2019 to 25 September 2019. Using the double proportion formula, we calculated the sample size using Open Epi V.2.3. The assumptions for the sample size calculation were alpha value 0.05; power 80%; exposed to non-exposed ratio 1:2 (proportion of adequate GWG=28% (exposure); and proportion of inadequate GWG=69% (non-exposure))30; proportion of LBW among women who gained adequate gestational weight=1.7%; proportion of LBW among women who gained inadequate gestational weight=17.5%,21 lost to follow-up=20%. The required sample was 189 (exposed=63 and control (non-exposed)=126). However, since this study was part of another large study, we recruited a sample size of 395. The details of the sample size calculation assumptions were described in the study published elsewhere.31 Pregnant women who came to health centres before or at 16 weeks gestation for antenatal care were invited to participate, and those who agreed were recruited. We limited eligibility to women with a singleton pregnancy and no comorbidities such as diabetes and hypertension. We used structured questionnaires with trained interviewers and face-to-face semistructured interviews during the baseline data collection. Using the questionnaires, we collected information regarding sociodemographic characteristics, previous history of abortion (termination of pregnancy before the 28th week of gestation), LBW and stillbirth, pregnancy intention (planned/unplanned), gravidity, food insecurity, dietary diversity, physical activity, intimate partner violence and depression-related symptoms. Data collectors measured baseline weight and height of the women and mid-upper arm circumference. Women’s medical records were also reviewed both during baseline data collection and after birth to collect data such as gestational age (ultrasound result), blood pressure, level of haemoglobin, random blood sugar result, weight at the 36th weeks of gestation, mode of birth, episiotomy, birth weight and sex of the baby. The primary author reviewed these data. Women were followed from before or at their 16th week of gestation until they gave birth to assess their GWG and the baby’s birth weight. Sixteen women (5.2%) gave birth in a rural location, and we could not access the birth records. The birthweight information was ascertained for these women through a phone call to the mother. The primary outcome variable in this study was birth weight. However, other pregnancy outcome variables such as the occurrence of gestational hypertension, modes of birth, episiotomy and birth outcomes (live birth, miscarriage or stillbirth) were also considered as outcome variables. We assessed the household food insecurity using the Household Food Insecurity Access Scale33 and the women’s dietary diversity using the minimum dietary diversity-women tool.34 Women’s physical activity level was measured using the International Physical Activity Questionnaire-long form.35 Perinatal depression symptoms were measured using the Edinburgh Postnatal Depression Scale36 and intimate partner violence were measured using a questionnaire used by the WHO multicountry study on women’s health and domestic violence.37 We double entered the data into Census and Survey Processing System (CSPro V.7.1). We exported data to STATA (V.14, StataCorp) for cleaning and analysis. Missing data were handled by performing pairwise deletion in the study. A particular variable was excluded when it had a missing value, but the case can still be used when analysing other variables with non-missing values. Hence, the analyses were performed on subsets of the data depending on where values are missing without completely omitting a case with missing some variables from the analyses. Descriptive statistics, including frequencies, means and SD, were computed to describe the data. We calculated GWG by subtracting women’s baseline weight from their weight at the 36th week of gestation. The adequacy of GWG (inadequate, adequate or excessive) was determined using the IOM criteria. Birth weight was analysed as a categorical and continuous variable. Birth weight was classified as <2.5 kg (LBW), 2.5 kg–3.9 kg (normal birth weight), ≥4.0 kg (macrosomia). The relationship between birth weight as a categorical variable (ie, LBW, normal birth weight or macrosomia) and other variables was reported descriptively using percentage. Since the number of LBW and macrosomic babies were small, we could not perform a regression analysis using birth weight as a categorical variable. Therefore, we assessed the influence of GWG and other variables on birth weight using a linear regression model. Variables with p<0.25 in the bivariable analysis were included in the multivariable analyses. However, some variable like food insecurity was considered important and forced into the multivariable model irrespective of the p value. The assumptions for linear regression were checked. Scatter plots showed that observations were linear. Multicollinearity was checked using the variance inflation factor (VIF). The mean VIF value was 1.44. The VIF value for each predictor variable was <3, which showed no multicollinearity among variables. We performed multivariable linear regression analysis to determine the independent effect of GWG on birth weight, adjusting for other potential factors (educational status, average household monthly income, and previous history of abortion (termination of pregnancy before the 28th week of gestation), consuming meat or chicken in the last 24 hours, food insecurity, prepregnancy weight, maternal haemoglobin level, occurrence of gestational hypertension and sex of the baby).