Effects of gestational weight gain on adverse pregnancy outcomes among pregnant women in gurage zone, central Ethiopia: a cohort study – Nature.com 06:33 

Scientific Reports volume 15, Article number: 6742 (2025) Cite this article

Abstract

The consequences of being overweight in non-pregnant individuals have been studied and chronic diseases are found to be associated with higher weight gain. However, few studies target the effect of gestational weight gain on adverse pregnancy outcomes. Thus, this study aims to fill the knowledge gap due to the scarcity of studies and inconsistencies of results and gain more insight into the effects of gestational weight gain on pregnancy outcomes. A prospective cohort study was conducted among pregnant women who started antenatal care follow-up before the 16 weeks of gestation in the selected health facilities of the Gurage zone. The follow-up continued until the first 7 days after delivery to record all the pregnancy outcomes. Adverse pregnancy outcomes include any of the following conditions: gestational hypertension, pre-eclampsia, eclampsia, gestational diabetes mellitus, antepartum hemorrhage, post-partum hemorrhage, preterm delivery, low birth weight, low Apgar score, intra-uterine death, intrapartum death, and early neonatal death. Binary logistic regression was used to assess the relationship between adverse pregnancy outcomes and other independent variables. From the 424 pregnant women included in the study, adverse outcome was documented among 31.4%, [95% CI 26.9, 35.8]. Maternal age, educational status of the mother, body mass index, and gestational weight gain were significantly associated with adverse pregnancy outcomes. Adverse pregnancy outcomes were higher among mothers with young age, no formal education, higher body mass index, and larger gestational weight gain.

The extent of weight gain during pregnancy is linked to the mother’s and the infant’s current and future health status1,2. The prevalence of overweight among reproductive-age women in Ethiopia has increased in the last two decades with dramatic change among the urban settlers3. The obesity epidemic has resulted in more overweight women before and during pregnancy4,5.

The consequences of overweight in non-pregnant individuals have been studied and cardiovascular and other chronic diseases are found to be associated with higher weight gain6,7,8. However, few studies target the effect of gestational weight gain on adverse pregnancy outcomes. Even those few studies were based in developed countries which are very different from our setting and their findings are not consistent.

Some literature identified the effects of gestational weight gain (GWG) on pregnancy outcomes depending on maternal nutritional status9,10. Inadequate/excessive weight gain in normal first-trimester weight doesn’t increase adverse pregnancy outcomes11. First-trimester overweight or excessive GWG may be associated with increased risks of poor pregnancy outcomes including gestational Diabetes Mellitus, hypertensive disorders of pregnancy, cesarean delivery, wound infection, and macrosomia12,13,14. Conversely, too little weight gain during pregnancy may intensify the risks of low birth weight15.

The effect of too much gestational weight gain may go beyond the mentioned adverse pregnancy outcomes and obstetric complications. It may also be associated with postpartum weight retention and may alter the metabolism of the mothers whose consequence may continue even up to a decade after delivery16,17,18.

Nevertheless, others described gestational weight gain as associated with pregnancy outcomes regardless of the first-trimester nutritional status of the mothers19,20,21,22. Others indicated no association between first-trimester weight and pregnancy outcomes. Still, some findings showed abnormal GWG is associated with poor maternal outcomes but not fetal outcomes. It’s unclear whether the effect of GWG differs depending on first-trimester nutritional status. Hence, prospective cohort studies are needed to further explore the association between gestational weight gain and adverse pregnancy outcomes23.

Poor pregnancy outcomes and related obstetric complications are common direct causes of maternal mortality, one of the top public health problems causing profound health burdens24,25. Thus, this study aims to fill the knowledge gap due to the scarcity of studies and inconsistencies of results and gain more insight into the effects of gestational weight gain on pregnancy outcomes using a prospective cohort study. The findings of this study will be used by the decision-makers and concerned stakeholders who work to improve pregnancy outcome.

Methods

Study area

The study was conducted in the Gurage zone, which is one of the zones in the southern nations and nationalities’ regional states. The capital of the zone is Wolkite town which is located 158 km from the national capital of Addis Ababa in the southwest direction. The zone has 13 woredas (districts) and 5 town administrations. There are nine functional hospitals in the zone, seven of which are public, and two of them are owned by non-governmental organizations. In addition, there are 64 governmental and six non-governmental Health centers and 412 Health posts in the zone.

Study design

We conducted a prospective cohort study involving pregnant women who attended antenatal care services in selected hospitals and health centers in the zone. We included women who started antenatal care follow up before 16 weeks of gestation at the time of enrollment. Recruitment of the study participants started on April 18, 2022, and the follow-up continued up to March 09, 2023. We measured their weight at baseline and just before delivery. We followed them until the first seven days after delivery to record all the pregnancy outcomes.

Study population

Pregnant women, who came for their antenatal care follow-up before 16th weeks of gestation at selected health facilities in the Gurage zone was the study population for the study.

Inclusion criteria

Pregnant women with singleton pregnancies and with no known Diabetes Mellitus (DM) and hypertension were included in the study.

Sample size determination

The sample size required for the study was calculated using Epi Info™ 7 software using a 95% confidence level, 80% power, 4.78% of the unexposed, and 12.69% of the exposed group developed gestational hypertension from a previous related study17, which gives a sample size of 402. Adding 15% to account for the loss to follow-up, the final sample size needed for this study was 463.

Sampling technique and procedures

Three Hospitals and five Health Centers were randomly selected. Considering the limited percentage of pregnant women with early antenatal care follow-up and low institutional delivery, consecutive samples of pregnant women were included. The details of the sampling technique and procedures have been presented elsewhere26.

Data collection techniques and procedures

Data were collected by trained data collectors and supervisors using pretested questionnaires. Data were also double-entered in to Epi Info software, cross-checked, and validated and all the discrepancies were resolved. The details about the data collection techniques and procedures have been presented elsewhere26.

Variables

Dependent variable

Adverse pregnancy outcome.

Independent variables

Operational definitions

Data processing and analysis

Data were entered into Epi Info 7 and exported to STATA version 17 for cleaning and analysis. Binary logistic regression was used to assess the relationship between adverse pregnancy outcomes and other independent variables. Bivariate logistic regression analysis was conducted to nominate candidate variables for multivariable logistic regression and those who had a p-value of < 0.2 were included in the multivariable model. The logistic regression model fitness was assessed by goodness-of-fit test using the Hosmer–Lemeshow test and the output indicated a well-fitted model, chi2(8) = 6.82, Prob > chi2 = 0.5560. Multivariable analyses were performed using logistic regression models and adjusted odds ratios were calculated and presented. The 95% confidence interval and p-value of less than 0.05 were used to decide the statistical significance of the associations.

We used the Variance Inflation Factor (VIF) to evaluate the degree of multicollinearity among the independent variables. We considered multicollinearity to be present if the VIF value was 10 or higher. In our study, the average values of the calculated VIF for all the independent variables were 1.63. This implies that multicollinearity is not a serious issue in our model and that the coefficients are reliable and meaningful.

We examined the effect modification of maternal nutritional status on the association between gestational weight gain and adverse pregnancy outcomes. We used the interaction term and plot to assess whether the probabilities of adverse outcomes differed by maternal nutritional status across different levels of gestational weight gain. We performed a chi-square test to check if the coefficients of the interaction term were equal to zero. A p-value greater than 0.05 and a parallel interaction plot indicated no significant interaction effect.

Results

Sociodemographic characteristics

From the calculated 463 samples, 424 were included in the study making the response rate 92%. The details about the sociodemographic characteristics of the study participants have been presented elsewhere26.

Reproductive and obstetrics characteristics

Pregnant women from 12-16th weeks of gestation were enrolled in the study, with a mean gestational age of 13.9 weeks. More than half (56.13%) [95% CI 51.4, 60.8] of them gained adequate weight, a quarter (26.42%) [95% CI 22.4, 30.8] of them gained inadequate weight, and the remaining 17.45% [95% CI 14.1, 21.4] of them gained excess weight during pregnancy compared to the IOM recommendation. Adverse pregnancy outcome was documented among 31.4%, [95% CI 26.9, 35.8] of the study participants (Table 1).Table 1 Reproductive and obstetric characteristics of women who gave birth in the selected health facilities of gurage zone, 2022.

Full size table

Factors affecting adverse pregnancy outcome

Controlling for potential confounder variables, maternal age, educational status of the mother, body mass index, and gestational weight gain were significantly associated with adverse pregnancy outcomes. Adverse pregnancy outcomes were higher among mothers with young age. Mothers in their late adolescence (15–19 years of age) were more than three times more likely to develop adverse pregnancy outcomes compared to mothers aged 25–34 years (AOR 3.40; 95% CI 1.41, 8.18). Additionally, mothers in their early twenties (20–24 years of age) were twice as likely to have adverse pregnancy outcomes as compared to mothers 25–34 years of age (AOR 2.07; 95% CI 1.05, 4.10). In comparison to mothers who attained college or more, those who did not have formal education were more than four times more likely to develop adverse pregnancy outcomes keeping other confounding variables constant (AOR 4.41; 95% CI 1.23, 15.83).

Body mass index was found to be significantly associated with adverse pregnancy outcomes. Controlling other confounding variables, the odds of adverse pregnancy outcome increase by 16% for one kilogram per meter-square increase of body mass index (AOR 1.16; 95% CI 1.00, 1.36). The amount of the gestational weight gained was significantly associated with adverse pregnancy outcomes. The odds of adverse pregnancy outcome increase by 10% with a one-kilogram increase in gestational weight gained given other factors kept constant (AOR 1.10; 95% CI 1.02, 1.19). There was no statistically significant association between adverse pregnancy outcomes and other independent factors like marital status, religion, occupational status, income, gravidity, and parity (Table 2).Table 2 Factors affecting adverse pregnancy outcome among women who gave birth in selected health facilities of gurage zone, 2022.

Full size table

We conducted a formal analysis of how maternal nutritional status modified the effect of gestational weight gain on the risk of adverse pregnancy outcomes. We employed the interaction term and plot to evaluate whether the likelihood of adverse outcomes varied by maternal nutritional status across different ranges of gestational weight gain. A p-value of 0.0449 and a parallel interaction plot indicated no significant interaction or effect modification (Fig. 1).

figure 1
Fig. 1

Discussion

This study tried to assess the effects of gestational weight gain on adverse pregnancy outcomes. Controlling for potential confounder variables, maternal age, educational status of the mother, body mass index, and gestational weight gain were significantly associated with adverse pregnancy outcomes. These findings are consistent with previous studies conducted in Pakistan and Thailand, which also found significant associations between body mass index and gestational weight gain and adverse pregnancy outcomes. This indicates that these factors may have a universal impact on pregnancy outcomes across different settings and populations22,33.

Therefore, it is important to monitor and manage these factors during prenatal care and to provide appropriate interventions that can improve the nutritional status and well-being of women of reproductive age, especially those who are younger, less educated, or have high body mass index. Moreover, it is important to provide adequate antenatal care and counseling to pregnant women to help them achieve optimal gestational weight gain and prevent pregnancy complications.

One of the strengths of this study is that we used a prospective cohort design, which enables us to investigate the causal relationship between exposure and outcomes. In addition, we have assessed multiple outcomes, such as gestational hypertension, pre-eclampsia, eclampsia, gestational diabetes mellitus, antepartum hemorrhage, post-partum hemorrhage, instrumental delivery, cesarean-section delivery, preterm delivery, low birth weight, low Apgar score, intra-uterine death, intrapartum death, and early neonatal death, to measure the comprehensive impact of the gestational weight gain on pregnancy outcome.

One of the main challenges that we encountered in conducting this study was the low coverage of antenatal care in the first trimester of pregnancy in the study area. This hindered our ability to apply probability sampling methods to select a representative sample of pregnant women who had received early antenatal care before 16 weeks of gestation. Instead, we had to include all the eligible women who attended the selected hospitals and health centers in the zones during the study period. Nevertheless, as the presentation of the pregnant women to the healthcare facility is expected to be random this may not have a significant impact on the external validity of our findings.

Conclusions

The result of this study revealed maternal age, educational status of the mother, body mass index, and gestational weight gain were significantly associated with adverse pregnancy outcomes. Other factors remained constant, adverse pregnancy outcome was higher among mothers with young age, no formal education, higher body mass index, and larger gestational weight gain.

Targeting teenage pregnancy by educating teenagers and the community about its consequences is very important to reduce adverse pregnancy outcomes. Improving the accessibility of formal education for young girls and women is imperative for their empowerment and favorable pregnancy outcomes. Health education and counseling services about healthy pregnancy during antenatal care should give due attention to women with higher body mass index and those with larger gestational weight gain.

Data availability

The datasets generated and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Abbreviations

BMI:

Body mass indexGWG:

Gestational weight gainIOM:

Institute of MedicineWHO:

World Health Organization

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Acknowledgements

It is our pleasure to forward heartfelt thanks to Wolkite University for funding this research project. We would like to express our deepest gratitude to the study participants, health professionals working at antenatal clinics of the selected facilities, data collectors, and supervisors for their efforts in ensuring quality data.

Funding

The research project was funded by Wolkite University and the funding organization has no role in the design of the study and collection, analysis, and interpretation of data and writing and submitting the manuscript.

Author information

Authors and Affiliations

  1. Department of Public Health, College of Medicine and Health Sciences, Wolkite University, Wolkite, EthiopiaGirma Alemayehu Beyene & Abebaw Wasie Kasahun

Contributions

GA: participated from the initiation to design of methodologies, data acquisition, analysis, and result writing, drafting, and reviewing the manuscript. AW: participated in the design, acquisition of data, analysis, report writing and interpretations, and critically reviewing the manuscript.

Corresponding author

Correspondence to Girma Alemayehu Beyene.

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Competing interests

The authors declare no competing interests.

Ethics approval and consent to participate

All methods and procedures were performed in accordance with approved guidelines and regulations, adhering to the principles of the Helsinki Declaration. The ethical approval was obtained from Wolkite University Institutional Review Board (Ref: RCSUILC/017/14). A letter of support was sent to the Gurage zone health office as well as the administrations of the selected health facilities (Ref: RCSUILC/018/14). Furthermore, the purpose of the study and the benefits of participating in this study were explained to study participants, and informed written consent was obtained. Information confidentiality was maintained throughout the course of the study and thereafter.

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Beyene, G.A., Kasahun, A.W. Effects of gestational weight gain on adverse pregnancy outcomes among pregnant women in gurage zone, central Ethiopia: a cohort study. Sci Rep 15, 6742 (2025). https://doi.org/10.1038/s41598-025-91782-7

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