4 Discussion

In our study, the adolescent pregnancy rate was 7.6%, lower than the rate reported in most developing countries.¹ In line with previous research^6,10 adolescent pregnant women had significantly lower levels of education than adult pregnant women. However, the access to prenatal care facilities and the number of prenatal care visits were similar to the adult group. Previous studies reported fewer numbers of prenatal care,^6,11 and less access to health insurance among adolescents.¹² Our study found that adolescent pregnant women living in rural areas were more common than adults, consistent with previous research.¹³ Similar to the adults, all adolescents in our study population were married. In Iran and most Islamic nations, teenage pregnancies occur under married status. Parents may arrange marriages for their young daughters for financial reasons or to preserve the girls' safety or honor.^14,15 When underlying diseases in adolescent pregnant women were compared to adults, adults had a higher prevalence of thyroid dysfunction and COVID-19. Anemia, cardiovascular disease, overt diabetes, pyelonephritis, hepatitis, and HIV were not statistically different between the two groups. However, gestational diabetes in adolescents was lower than in adults. These findings were consistent with previous studies.^6,16

In our study, the risk of adverse events such as preeclampsia, placenta abruption, placenta previa, fetal distress, preterm labor, shoulder dystocia, perineal lacerations, childbirth trauma, congenital malformation, postpartum hemorrhage, maternal death, stillbirth, maternal and neonatal intensive care unit admission, and neonatal death was not high in adolescents. According to the findings of this study, adolescent mothers were more likely than adults to have meconium fluid, LBW, and IUGR rates based on the chi-square test; however, we found that when covariates were adjusted for in the regression models, teenage pregnancy did not increase the risk of poor birth outcomes. Adults, on the other hand, had a higher risk of CS than adolescents, which was expected given that most adults were multiparous and some of them had previous CS, so it is possible that a significant amount of CS in adults was repeated CS. However, it should be mentioned that even after adjusting for the history of previous CS, the risk of CS in adults was higher than in adolescents. Analyzing the indications of CS revealed that for teenage mothers, the indications were mostly due to fetal distress, whereas for adults, the indications were mal-presentation and previous CS. The COVID-19, which was significantly higher in adults, could be one reason for the higher rate of CS, given that approximately 64% of pregnant women with COVID-19 delivered via cesarean route according to one study.¹⁷ Another study in Wuhan, China found that 93% of pregnant women with COVID-19 had CS.¹⁸ Another reason for the higher rate of CS in adults could be the higher rate of gestational diabetes, leading to fetal macrosomia. Women with gestational diabetes have a higher risk of CS than glucose-tolerant women.¹⁹

Adolescent pregnancy is frequently associated with poor outcomes for both mother and child. The effect of maternal age on obstetric and neonatal outcomes has been studied in different parts of the world, with varying results. In contrast to our findings, previous research has found an increase in poor maternal and neonatal outcomes such as LBW,^6,20 stillbirth,²¹ preterm labor,^6,20 and maternal death.^10,22 Adolescent mothers were at higher risks of eclampsia, puerperal endometritis, and systemic infections than mothers aged 20–24 years in a WHO multicountry study involving 29 low- and middle-income countries ^[23]. Another study by Aka et al. found that adolescent pregnancy was associated with adverse pregnancy outcomes ^[24]. A variety of factors, including differences in sample size, medical service quality, and the social and cultural backgrounds of women and their families, could account for the contradictory results found in previous studies and this one.

Adolescent mothers are more likely to have a poor pregnancy outcome because of social determinants of health. For example, poor pregnancy outcomes in adolescent mothers are associated with rural residence, insufficient education, and low socioeconomic status.⁵ Based on our findings, even though more adolescents than adults lived in rural areas and had lower levels of education, they had comparable levels of medical insurance, access to prenatal care, and an adequate number of prenatal care visits. Cities in Iran provide free prenatal care to nearly all pregnant women, including visits to general practitioners and midwives. Specialized maternity units in public hospitals handle almost all obstetric patients and births. As a result, regardless of socioeconomic status or place of residence, everyone has access to comprehensive prenatal care. This reduces the confounding effects that frequently complicate such studies. In addition, all of the adolescents were married, so we can infer that they had the support of their families. We hypothesized that the previously mentioned factors are protective against a poor prenatal outcome even though they were not explicitly tested in our research. However, it remains unclear whether poor pregnancies among adolescent mothers result from biological immaturity or poor socioeconomic circumstances. More research is needed to gain a more comprehensive perspective.

We found contradictory data here; adolescent women had no worse pregnancy outcomes. We believe this is due to adequate access to prenatal care, health insurance, and family support. We believe that these can be used in other countries. We understand that some ethnic differences might be in the way to fulfil them; however, the present data might be of use and generalizable to any other countries which faced many difficulties due to adolescent pregnancies.

The strength of our study is that our study registers are of high quality and in accordance with childbirth records. We investigated various factors associated with adolescent pregnancies, including pregnancy, childbirth, and neonatal outcome. The population study sample size was large enough to reflect the situation regarding obstetric challenges among all adolescent pregnancies during the study period. Our study was conducted retrospectively, which is still a limitation. The database did not allow for the precise timing of the various events during pregnancy. More data was missing for some variables, such as body mass index and weight gain during pregnancy, known as risk factors for adverse prenatal outcomes. Because our study group of 13- to 15-year-olds was small in size, we lacked the power to detect risks of rare outcomes; thus, we did not conduct a subgroup analysis to determine the effect of very young age on the risk of adverse obstetric outcomes.