The association between combined oral contraceptive use and overweight/obesity: a secondary data analysis of the 2016 Ethiopia Demographic and Health Survey

Abstract

Objectives

In this study, we aimed to assess the association between combined oral contraceptive (OC) use and overweight/obesity among Ethiopian adult women of reproductive age.

Design, setting and participants

The data were extracted from the 2016 Ethiopia Demographic and Health Survey; these data were collected from nine regions and two city administrations. We analysed the data from a total of 11 018 women aged 18–49 years who met eligibility criteria.

Main outcome measures

We employed WHO criteria to classify the body mass index of women. Specifically we tested the association between combined OC utilisation with overweight/obesity after controlling for confounding variables.

Result

The prevalence of combined OC utilisation was 1.7% and the prevalence of overweight/obesity was 8.6% among adult women of reproductive age. Use of combined OC increases the odds of overweight/obesity by two times among adult women of reproductive age after controlling for potential confounders (adjusted OR=1.902 (1.064–3.399)).

Conclusion

In conclusion there is significant association between combined OC use and overweight/obesity. The findings have important implications for policymakers to design evidence based policy approachs to obesity prevention for women and at large for government to recognise the negative consequences of combined OC on women health.

Strengths and limitations of this study.

• In the multivariable analysis, confounders were controlled.

• The sample size was large and adequate; this increases precision of the findings.

• The ethical clearance fulfilled national protocols.

• Household economic status was assessed through the Wealth Index.

• There is an absence of variables such as duration of combined contraceptive use in the data set.

Introduction

Recently the prevalence of overweight/obesity increased both in the developed world and the developing world. WHO defines overweight and obesity as abnormal or excessive fat accumulation that may impair health,¹ which is associated with many chronic diseases, such as diabetes mellitus, heart diseases, hypertension and some forms of cancer.^2–4

In 2016, more than 1.9 billion adults (18 years and older) were overweight. Of these over 650 million were obese.¹ Previously, overweight/obesity was considered as a problem of high-income countries; now this has emerged in low-income and middle-income countries also, particularly in urban settings.⁵

A study which analyses the demographic and health survey data of 23 sub-Saharan African countries revealed that the pooled prevalence of overweight was 15.9%.⁶ Obesity leads to metabolic disorder⁷; specifically during pregnancy, its effects result in adverse neonatal outcome, caesarean section^8–10 and maternal morbidity.¹¹ The effect of obesity does not end with this; it also results in breast and ovarian cancers.¹²

The risk of obesity was higher among users of hormonal contraceptives due to the effect of progesterone. Progesterone induces appetite or facilitates anabolism and oestrogen aggravates the accumulation of fat in the cell or adipose tissue. It was seen that the effect increased as the duration of hormonal contraceptive utilisation increased.¹³ Similarly a study conducted in Kenya and Myanmar indicates that overweight/obesity was significantly correlated with hormonal contraceptive use.^{14 15}

A study conducted among premenopausal women in Korea and Spain revealed that oral contraceptives (OCs) have a significant association with overweight/obesity.^{16 17} In contrast other researchers concluded that OC had no association with obesity or weight gain.^{1 18} Besides; an evidence drawn from a systematic review concluded that there is nosufficient scientific evidence to generalize whether combined oralcontraceptive have significant association with overweight/obesity or not.¹⁹

Most studies conducted previously have shown that obesity affects the efficacy and effectiveness of combined OCs,^20–25 but but other studies showed that obesity had no effect on COC efficacy and effectiveness.^26–28

Additionally some researchers have pointed out the effects of OC on ovarian cancer, polycystic ovary syndrome and cardiovascular disease.^29–32

In the Ethiopian context different researchers have extensively identified the determinant factors of overweight/obesity,^33–42 but none of them depicted the correlation between combined OC use and overweight/obesity.

Generally there is controversy on the effect of combined OC use on the development of overweight/obesity. Therefore we intend to assess the association between combined OC use and overweight/obesity among adult women of reproductive age.

Methods and materials

Study design and population

The 2016 Ethiopian Demographic Health Survey (EDHS) was designed to provide up-to-date estimates of key demographic and health indicators in Ethiopia. The data were collected from nine regions and two city administrations. A detailed description of the study design and methodology of the 2016 EDHS was found elsewhere.⁴³ In brief, a stratified two-stage random sampling design was used to collect the data from a nationally representative sample. In the first stage, a total of 645 enumeration areas (EAs) (202 in urban areas and 443 in rural areas) was selected through probability proportional to EA size. In the second stage, 28 households per cluster was systematiclly selected with an equal probability of selection. Data were obtained from the DHS programme website: https://www.dhsprogram.com.

A total of 15 683 women aged 15–49 years was interviewed in the 2016 EDHS. Those women with missing data on the question related to the outcomes of interest and other covariates were excluded. In this paper, we restrict our analytical sample to 11 018 non-pregnant women aged 18–49 years (figure 1).

Figure 1.

Flow diagram of selection of study participants.

Measurement of height and weight of women

The weights and heights of the mothers were measured with standard weighing and height scales. The weight of the women was measured to the nearest 100 g on a calibrated portable digital scale (the UNICEF electronic weighing scale) after removing shoes and wearing light clothes. The height was measured to the nearest 0.1 cm in the erect position with their shoulders levelled, hands at the side, and the head, scapula, buttocks and heels in contact with a vertical measuring board with a sliding head bar.

Body mass index (BMI) was calculated by dividing weight in kilograms by height in square metres (kg/m²). The classification of BMI was taken from the WHO standard, that is, BMI <18.5 = ‘underweight’, BMI=18.5–24.9 = ‘normal weight’ and BMI ≥25 = ‘overweight/obese’.⁴³ In the current study, BMI ≥25 kg/m² is considered as overweight/obese and BMI ≤24.9 kg/m² is considered as non-overweight/obese.

Measurement of combined OC utilisation

The exposure variable was combined OC utilisation. The exposure variable was dichotomized to create a binary variable to reflect either she used combined OC during the survey or not. Women who responded ‘Don’t know’ were excluded. The COC utilisation and other covariates were collected through a questionnaire.

Statistical analysis

The data were analysed through the IBM Statistical Package for Social Sciences V.22 (Armonk, New York, USA). The frequencies and percentages of the study variables were displayed in tables. Both binary and multivariable logistic regression analysis was conducted to control possible confounders. The Wealth Index was used to measure the household economic status. It is taken from the 2016 EDHS and categorised as poor, middle and rich. Adjusted ORs with 95% CIs were used to declare an association.

Patient and public involvement

Patients and the public were not involved in this study.

Results

Participants’ characteristics

The prevalence of overweight/obesity was 8.6% in the current study. Of the total of 11 018 women who participated in the study, 56% were uneducated and 75.2% had got married. Almost all women had no cigarette smoking history before the survey and more than two-thirds (72.3 %) did not watch television. Among the participants included in the study 67.3% did not use any family planning method. Regarding the contraceptive method used, 67.3% did not use any and 32% used modern family planning. In the current study the proportion of women who had used combined OC was 1.7% (table 1).

Table 1.

Sociodemographic and behavioural characteristics of the study sample (n=11 018)

Variables	Category	N (percentage)
Age in years	18–24	7188 (65.4%)
	35–49	3830 (34.6%)
Educational status	No education	5684 (56%)
	Primary	2985 (27.7%)
	Secondary	1362 (9.8%)
	Higher	987 (6.6%)
Marital status	Single	1670 (13.6%)
	Married	7962 (75.2%)
	Widowed	421 (3.7%)
	Divorced/separated	965 (7.5%)
Occupation	Not working	5510 (50%)
	Professional	2810 (25.5%)
	Agricultural/skilled/unskilled	2698 (24.5%)
Wealth Index	Rich	5430 (45.9%)
	Poor	4181 (34.8%)
	Middle	1407 (19.2%)
Smoke cigarettes	No	10 905 (99.3%)
	Yes	113 (0.7%)
Alcohol intake in the past 12 months	Almost everyday	259 (6.2%)
	At least once a week	1236 (32.9%)
	Less than once a week	2302 (57.8%)
	None in the last 12 months	141 (3.1%)
Frequency of watching television	Not at all	7114 (72.3%)
	Less than once a week	1267 (12.2%)
	At least once a week	2637 (15.5%)
Current contraceptive use by major method	No method	7984 (67.3%)
	Traditional method	86 (0.6%)
	Modern method	2948 (32.0%)
Current use of contraceptive by method type	Not using	7984 (67.3%)
	Pill	221 (1.7%)
	IUD	180 (1.9%)
	Injections	1726 (20.3%)
	Male condom	43 (0.1%)
	Female sterilisation	27 (0.4%)
	Periodic abstinence	74 (0.5%)
	Withdrawal	12 (0.1%)
	Implants/norplant	722 (7.4%)
	Lactational amenorrhoea	12 (0.1%)
	Emergency contraception	5 (0.01)
	Standard days method	12 (0.1%)

IUD, intrautrine device; N, Number.

Association between COC use and overweight/obesity

Generally combined OC utilisation was significantly associated with overweight/obesity. Multivariable logistic regression analysis showed that women with a history of combined OC use had an increased odds of overweight/obesity after controlling for potential confounders (table 2).

Table 2.

Association between OC use and overweight/obesity among adult women of reproductive age (n=11 018)

OC use	Overweight/obesity
	OR (95% CI)
Unadjusted analysis
No	Ref
Yes	2.798 (1.615 to 4.85)
Multivariable analysis*
No	Ref
Yes	1.902 (1.064 to 3.399)

*Adjusted for age, educational status, marital status, occupation, Wealth Index, cigarette smoking status, alcohol intake and watching television.

OC, oral contraceptive; OR, odds ratio; Ref, reference.

Discussion

The present study assesses the association between combined OC utilisation and overweight/obesity at the population level in Ethiopia among adult women of reproductive age who participated in the 2016 EDHS. The results showed that there is a positive association between combined OC utilisation and overweight/obesity after controlling for potential confounders.

The current result is supported by⁴⁴ a study among premenopausal girls in Korea; they found that using COC for more than 6 months increased the occurrence of obesity and this was higher among women whose dietary intakes of calcium, phosphorus, potassium, vitamin A, vitamin B₁, vitamin B₂, niacin, vitamin C and folate were lower than the recommended values. But for those women whose intakes of those nutrients were above the recommended values there was no significant relation between OC use and obesity. Another prospective cohort study among university graduates revealed that prolonged use of OC (more than 2 years) was significantly associated with the development of obesity in the middle-aged and free-living Spanish population.¹⁷ Additionally similarly findings have been reported in studies conducted elsewhere.^{14 15 39}

A possible explanation for the observed positive association between combined OC use and overweight/obesity might be hormonal effect of OC that contribute to weight gain.⁴⁵ Indeed; the obesity is mainly due to the pharmacodynamic effects of progesterone and oestrogen. Progesterone increases appetite and results in faster metabolism. Additionally oestrogen facilitates lipid metabolism and fat accumulation in the adipose tissue in the cell. As a result combined OC users are at a risk of developing overweight/obesity.¹³

Limitations of the study

This study has several limitations. First, the absence of important variables that contribute to obesity, such as intensive physical activity, transportation method and dietary habit in the 2016 EDHS. Second, lack of research papers on the topic makes the discussion difficult. Finally, the cross-sectional design of the present study precludes conclusions regarding a causal link between combined OCs and overweight/obesity.

Conclusion

In conclusion, the present population-based study supports previous scientific evidence. We conclude that there is a significant association between combined OC use and overweight/obesity among women. The adjusted findings from the present population-based study can be generalised and applied to the entire female population of reproductive age in Ethiopia. The findings have important implications in designing the mechanism for controlling obesity in women. At the national level, the Ethiopian Minstry of Health should give attention for the negative consequences of combined OC on women health since overweight/obesity is another killer of women. It will be better if future researchers conduct a follow-up study to know the real association and provide sound scientific explanations.

Data availability statement

The data sets used for this manuscript are available from the corresponding author upon reasonable request.

Ethics statements

Patient consent for publication

Not required.

Ethics approval

The data were downloaded once approval was obtained from Measure DHS. The original DHS data were collected in confirmation with international and national ethical guidelines. The 2016 EDHS protocol was reviewed and approved by the Federal Democratic Republic of Ethiopia Ministry of Science and Technology and the Institutional Review Board of ICF International.