Teenage pregnancy rates and associations with other health risk behaviours: a three-wave cross-sectional study among South African school-going adolescents

High teenage pregnancy rates are reported in both LMICs and HICs. The rate of teenage pregnancy in the United States is among the highest (at about 24 %) of the HICs [1] while more than 50 % of all births occurring during adolescence are in sub-Saharan Africa [2]. Globally, almost 16 million girls aged 15 to 19 give birth every year [2] and about 2.5 million of these births occur to girls aged under 16 in LMICs each year [3]. This is about 11 % of all births worldwide, with the majority of these (95 %) occurring in LMIC [2]. Complications during pregnancy and childbirth worldwide are the second leading cause of death for 15–19 year-old girls, with girls below 16 years of age at a higher risk for maternal mortality and severe morbidity in comparison with women above the age of 20 years [2‐6]. In addition, birth outcomes for very young adolescent mothers are particularly poor in terms of increased rates of low birth weights [6, 7]. Furthermore, teenage pregnancy is a major contributor to a never ending cycle of ill-health and poverty worldwide [2, 4‐6].

Teenage pregnancy in SA is a multifaceted problem with many contributing factors such as poverty, gender inequalities, gender-based violence, substance use, poor access to contraceptives and issues with termination of pregnancy; low, inconsistent and incorrect use of contraceptives, limited number of healthcare practitioners and healthcare facilities, poor healthcare workers’ attitudes and behavior, and inadequate sexual and reproductive health (SRH) information [6‐9]. Besides these structural and healthcare systems related factors, adolescents in general tend to engage in risky behaviours including sexual activities that eventually put them at risk for unwanted pregnancies, sexually transmitted infections (STI’s), and HIV [10]. Sexual risk-taking behaviours, including early sexual debut, unprotected sex, multiple sex-partners and low contraceptive use are common among young people in SA [10‐12], even though the SA government has made the provision of contraceptives free since 2001. The government continues to update and upgrade the scope of contraceptives in the country, including the addition of the very modern forms of contraception such as implants that are available in the public state hospitals and in primary healthcare clinics since 2014 [13‐15]. Since 1994, emergency contraceptives and maternal and child healthcare services are free of charge while termination of pregnancy (TOP) has been legal and is also provided free of charge since 1996.

There exists a large body of literature worldwide on factors associated with teenage pregnancy and early childbearing both in HIC and in LMIC, such as low levels of contraceptive use. For example, a study on contraceptive use among adolescents in Kenya reported the use to be low, despite the reported high levels of knowledge about contraceptives among this population [16]. In SA, a few studies have also reported on the factors associated with teenage pregnancy and other sexual risk behaviours such the low use of contraceptives and poor knowledge of contraceptives, amongst others mentioned above [12, 17‐20]. The reproductive health ignorance among young people, such as the basic understanding of a pregnancy possibility as a consequence of unsafe sexual intercourse, is also contributing to teenage pregnancy [21]. Unsafe sex is common among South African adolescents and is known to result in a number of unpleasant health and social consequences [9, 12, 20‐24]. Teenage pregnancy in SA is on top of the list of consequences of unsafe sex, following HIV and AIDS, and other STI’s.

Sexual risk behaviors and substance use often occur in combination with one another, both in developed countries as well as in LMIC [25‐28]. Substance use, particularly marijuana and cocaine, continue to represent individual-level risk factors associated with adolescents sexual behaviors, including use of contraception, safe sex practices, and teenage pregnancy [25]. Furthermore, substance use among adolescents, especially alcohol and drugs has been reported to influence what adolescents do sexually, and makes them less likely to practice safe sex [26]. Substance use behaviors in general, independently contribute to an increased risk in sexual intercourse experience with and without a history of teenage pregnancy [25, 26]. A dose-response relationship between an increased likelihood of a teenage pregnancy and both marijuana use and daily cigarette smokers who initiated use at age 12 or younger was reported among adolescents in the United States (US) [26]. Substance use in SA has been associated with higher odds of lifetime sexual intercourse [27]. High school adolescents who used alcohol or smoked cigarettes were two to three times more likely to be sexually active in the KwaZulu-Natal province [28].

There is clearly a lot of literature on teenage pregnancy, but its scope is limited to the causes of teenage pregnancy [21], the implications of pregnancy to the young mother (and her baby) [22, 29], and to school dropout related factors [22, 24]. There are however, very limited studies published that report on recent trends in teenage pregnancy in SA [29]. Even less is known about the factors associated with trends in teenage pregnancy. Analysis of teenage pregnancy trends and the associated factors is of paramount importance, as it will help to understand fully the factors surrounding teenage pregnancy in SA. It provides useful information towards understanding the magnitude of teenage pregnancy among the South African youth and helps determining areas that require serious intervention efforts in order to reduce the rates of teenage pregnancy. Understanding the factors or determinants associated with teenage pregnancy is crucial because it is this understanding that will enable development of intervention programmes needed to address teenage pregnancy in the country. Thus, the aim of this particular study is to examine the trends in teenage pregnancy as well as related health risk behaviors, including unsafe sex, substance use, partner violence, and psychological well-being; which might act as contributory factors associated with teenage pregnancy among school-going adolescents between 11 and 19 years of age in different settings of the country.

The SA YRBS used a two-stage cluster sample design. At the first stage of sampling, schools were stratified according to the country’s nine provinces. For each sample the most recent list of all public schools in the country, provided by the South African National Department of Education, was used as the sampling frame, to ensure nationally representative data. The schools were the primary sampling units and were selected with a probability proportional to the schools’ adolescent enrolment in grades 8 to 11. In each survey twenty-three schools per province were sampled and invited to participate. At the second stage of sampling, classes were randomly selected within each participating school. A total of 14 766 (for 2002 survey), 13 379 (for the 2008 survey) and 14 387 (for the 2011 survey) enrolled adolescents from grades 8–11 in the participating schools per province were invited for each survey respectively. Nationally, a 72 % response rate for 2002 and 2011, and 76 % for 2008 was achieved at the adolescent level.

Adolescents completed a self-administered questionnaire on a range of socio-demographic characteristics and risk behaviour variables. The YRBS questionnaire was adapted from the US Youth Risk Behaviour Survey, a health survey conducted biennially among high school adolescents in the United States [30]. The measures used in the study are specified below. Further details regarding the South African YRBS survey and methodology can be found elsewhere [31‐34].

Ethical Approval for the study was obtained from the South African Medical Association Research Ethics Committee. Active informed consent to conduct the study was obtained from the National Department of Education, school principals, parents and learners. In addition, assent was also obtained from learners on the day of the study. Learners were requested not to write their names on the answer sheet to ensure their anonymity. To ensure learners’ confidentiality, only trained survey administrators were allowed to remain with the learners while completing the survey. School teachers were requested to leave the classroom during data collection time. Learners were also requested not communicate with each other or look at the answer sheet of their peers during the completion of the survey. Information sheet regarding the surveys was also provided to the learners.

Frequency data were weighted to approximate province level distributions of gender and grade, and to account for non-response and province size. Weights were post-stratified by grade and gender, so that the weighted counts of students in each grade and gender combination were in proportion to the provincial population proportions. Each province was to be represented equally in the sample. To account for the variations in provinces’ total population, respondents in highly populated provinces had to have higher weights than respondents from less populated provinces. The three different YRBS data sets were combined for the trend analysis purposes. The trend analysis followed the protocol on Conducting Trend Analysis of YRBS data published by the US Center for Disease Control [35]. Descriptive statistics were first explored to gain a clearer picture of the data as well as to summarize the characteristics of the overall sample. The combined dataset was then split according to the respective years. Frequencies were run for each survey to provide overview differences in characteristics for the three surveys. This provided insight into trends in teenage pregnancy and sexual activity behaviours among adolescent who reported to have ever had sex in the three different surveys. Trends were considered significant if 95 % confidence intervals did not include 1 and the p-value was below 0.05. Bivariate correlation analysis was performed to establish risky behaviours associated with teenage pregnancy.

Collinearity statistics showed the variables taken into the logistic regression model did not violate the multi-collinearity assumptions: all the variables in the model were below the cut off value for the variance inflation factor (VIF) of 10 [36, 37]. The adjusted relationships of these measures for ever been pregnant were modelled in a binary logistic regression model. A significance level of 5 % was used for all analyses. IBM SPSS Version 21.0 was used to analyse the data. Description of sexual risk behaviours, bivariate correlations, and the logistic regression analysis (Tables 2, 3 and 4) only included adolescent girls (N = 5060) who reported to have ever had sex.

The first important finding in this study is that sexual intercourse among adolescents has decreased. However, among those adolescent girls who reported to engage in sex, teenage pregnancy has increased. These findings are in line with increasing evidence demonstrating the magnitude of teenage pregnancy among sexually active adolescents, especially in the sub-Saharan African countries [1, 2, 4, 19, 20]. This is worrying, particularly the fact that it suggest that there is little progress made in reducing teenage pregnancy over the past few decades, despite its importance as highlighted in the Millennium Development Goals (MDG) and its association to maternal mortality and morbidity rates [5]. Teenage pregnancy in developing countries has been reported to be worse than in developed countries [4, 5]. The lack of data on teenage pregnancy trends among South African adolescents poses a serious public health threat, as the magnitude of the problem is relatively hidden for consideration into intervention programs that aim to reduce teenage pregnancy, and improve maternal and child health outcomes. The fluctuating rates of sexual intercourse at the age of 13 years or younger among girls is also concerning. Early sexual debut is not uncommon in SA. Recent research shows that more and more adolescents are sexually active by the time they are 14 years and older [25, 38].

This study shows that the trends in teenage pregnancy have remained steady from 2002 to 2011. When looking at those girls who reported to ever had sex, teenage pregnancy has even increased from 2002 (17.3 %) to 2011 (21.3 %). The increased pregnancy rates among these girls can be attributed to, among other factors, the fewer girls who are using contraceptive methods to prevent pregnancy but are sexually active in this study, despite the fact that contraceptives are available for free at the public healthcare settings in the country. Contraceptives, which are directly provided from the healthcare setting, such as birth control pills and contraceptive injections, are among the least of contraceptive methods used by adolescent girls in this study. The findings of small proportion of girls using modern contraceptives, such as birth control pills is surprising given the fact that contraceptives are provided free of charge in SA [13‐15]. However, this can be explained by (1) the poor knowledge of contraceptives among adolescents in general in SA [29, 38], and (2) the limited availability of, and access to sexual and reproductive health services targeted at adolescents [39, 40]. Furthermore, the cultural or societal, structural, and individual factors associated with the use of contraceptives are some of the barriers for contraceptive use [40, 41]. These include, the need to prove fertility and maturity by the girls, opposition from male partners, perception of personal low risk around the ability to fall pregnant, and fear of side effects [12, 16, 41‐43]. On one hand, low levels of contraceptive use and the attitude toward using them among adolescents has been associated with high rates of unwanted pregnancies and unsafe abortions among youth in Sub-Saharan Africa [40, 42]. On the other hand, low levels of contraceptive use has also been attributed to limited capacity of the health care system, particularly in rural settings and structures within which family planning services are offered [6]. There is increasing evidence on the youth unfriendliness of the primary health care facilities in the country, which in turn might be a contributing factor to the poor use of contraceptives among adolescents; and thus exacerbate the trends in teenage pregnancy in SA [43‐45].

The second important finding in this study is that girls who use condoms when having sexual intercourse were less likely to get pregnant as a teenager. This finding supports previous research on reported knowledge and potential benefits of consistent and correct condom use by most young people in SA [43, 44]. It is well known that condom use during sexual intercourse not only prevents unwanted pregnancy; but also prevents contraction of HIV and other STIs [43, 44]. This finding also shows that the efforts made by the government in making condoms free of charge and easily accessible are beneficial to the youth of SA [9, 43, 45]. This is also in line with research findings from HICs where decline in teenage pregnancy is attributed to improved contraceptive use, including condom use [46]. Therefore, continuous efforts on encouraging and facilitating condom use among young people in SA still proves to be an important behavioural intervention worth investing in, both for the prevention of HIV and other STIs’ transmission and for contraceptive purposes.

Thirdly, girls who have sex with only one sexual partner in this study were also less likely to fall pregnant compared to the girls who had 2 or more sexual partners during their teenage years. Multiple sex partners is common in SA and has gender and cultural connotations, especially in KwaZulu Natal (KZN) and the Eastern Cape (EC) rural communities [9, 44, 45, 47]. Having more than one sexual partner for boys in KZN, as well as in the EC proves “masculinity” among boys, while for some girls it guarantees peer approval although it has to be discreet among girls [6, 9, 44, 47, 48]. This highlights another important area needing intervention for behaviour change, since a quarter of the girls in this study reported to have sex with 2 or more sexual partners.

The fourth and last finding of this study is the larger proportion of adolescents using alcohol and drugs. Clearly, alcohol and substance use among adolescents also requires attention. About half of the adolescents in this study have used alcohol one or more times in their lives. Substance use, in a few studies has been linked to teenage pregnancy. A study in Sweden reported that smoking and binge drinking among males was associated with the likelihood of the males having made their partners pregnant [49]. In this study, girls who never use alcohol before having sex, not practice binge drinking, who do not smoke cigarettes and do not use mandrax were less likely to fall pregnant as a teenager. The risk factors associated with teenage pregnancy, including alcohol use, smoking (tobacco or drug use) were also reported by Imamura et al., (2007) [50]. The author reported that these health risk behaviours tend to co-occur with teenage pregnancy in the European countries. Some studies have also reported on the possible link between teenage pregnancy and alcohol, and or tobacco and drug use [50‐52]. The findings of this particular study show that substance use increases the likelihood of adolescents falling pregnant during their teenage years. This is in line with previous findings that these risk behaviours, especially alcohol use, have been associated with other sexual-risk taking behaviours that result in pregnancy [53]. This study also found that girls who had a father who is unemployed or deceased were more like to get pregnant; and in terms of race, girls who belonged to the White race were less likely to become pregnant than other races. This finding supports previous research where low socio-economic status was found to be associated with teenage pregnancy in SA [20, 26, 27]. It is well documented in SA that teenage pregnancy is much more prevalent among the poor Black Africans [20, 26].

A limitation of the study at hand is that it is undertaken in the school setting. This excludes those adolescents who were not schooling at the time of data collection. Teenage pregnancy has been reported to be the most common reason for school-dropout in SA [26, 28]. Therefore, some adolescents might be out of school as a result of pregnancy and that does not invalidate the findings of this study, which confirms teenage pregnancy is still prevalent among adolescents in SA. Another limitation is that the results of this study cannot prove causality of teenage pregnancy by these risk behaviours, but only associations with teenage pregnancy. Thus, future research should aim to mitigate the risk behaviours associated with teenage pregnancy, as reported in this study. The pattern in teenage pregnancy is clearly increasing among those who engage in sexual activities, and that is a cause for concern. This suggests the further need to address health risk behaviours, including early sexual debut, unsafe sex, substance use and encouraging the correct and consistent use of contraceptives among adolescents; as well as promote their sexual and reproductive health in SA.

Sexual intercourse among adolescents is decreasing, but teenage pregnancy continues to increase among those who are sexually active. Teenage pregnancy continues to be a growing public health concern and adolescent sexual and reproductive health behaviours, such as contraceptives and safe sex practices has to be acknowledged in the health care system as an important health issue in SA. Risky behaviours, such as substance use, also need to be recognized and intervention programmes aiming to reduce teenage pregnancy and sexual and reproductive behaviours among adolescents need to include prevention of substance use. This study highlights the need for more comprehensive research on adolescents SRH needs particularly among the vulnerable adolescents aged 16 years and under, but not excluding those aged above 16 years old, to identify risk factors and develop specific interventions tailored for their needs. Regular monitoring of teenage pregnancy trends and the associated factors also aid in determining the effectiveness of programmes put in place by government and other related institutions, as well as highlighting areas where extra effort is needed to curb the rates of teenage pregnancy.