Descriptive characteristics:
After exclusions, 11,194 adolescents between the ages of 15 and 19 were included in our analysis. Of these adolescents, 16% were married or cohabited, with 31% of those married before the age of 16. 51% of the entire sample had first sexual intercourse before the age of 16, 51% of adolescents had partners between the ages of 20–24, 73% lived in a household with a man as head of household, 7.3% had experienced physical violence, and 13% had experienced sexual violence. 44.9% of participants had less than secondary school education, 18% were currently employed and 23% were not able to read. 46% were living in urban areas, with 17% in Lusaka, and 26% in the richest wealth index. As composite variables, 98% of adolescents had knowledge of adolescent sexual and reproductive health services (ASRH), and 55% had utilized them in the past (Table 1).
Table 1
Descriptive characteristics of study participants (N = 11,194)
Variable | Characteristics | N(%) |
Marital status | 0 = never married 1 = married or cohabitating 2 = divorced or separated | 9280 (83) 1767 (16) 146 (1.3) |
Age at first cohabitation (N = 975) | 1 = < 16 years 2 = 16–19 years | 594 (31) 1318 (69) |
Age at first sex (N = 2203) | 1 = < 16 years 2 = 16–19 years | 2668 (51) 2515 (49) |
Sex of household head | 1 = Male 2 = Female | 8194 (73) 2999 (27) |
Age of most recent partner N = 4198 | 1 = < 19 years 2 = 20–24 years 3 = 25–29 years 4 = 30–39 years 5 = 40–49 years | 899 (21) 2139 (51) 615 (15) 123 (2.9) 422 (10) |
Physical violence | 0 = No 1 = Yes | 1365 (93) 108 (7.3) |
Sexual violence (N = 757) | 0 = No 1 = Yes | 1281 (87) 191 (13) |
Employment status (N = 5162) | 0 = Not currently working 1 = Currently working | 9109 (82) 2053 (18) |
Place of residence (N = 5193) | 1 = urban 2 = rural | 5144 (46) 6050 (54) |
Region (N = 5193) | 1 = Central 2 = Copperbe 3 = Eastern 4 = Luapula 5 = Lusaka 6 = Muchinga 7 = Northern 8 = North west 9 = Southern 10 = Western | 1076 (9.6) 1959 (18) 1302 (12) 805 (7.2) 1959 (17) 772 (6.9) 836 (7.5) 710 (6.3) 1187 (11) 587 (5.2) |
Literacy (N = 5130) | 0 = Cannot read 1 = Able to read parts of sentence 2 = Able to read whole sentence | 2575 (23) 1515 (14) 7038 (63) |
Wealth index (N = 5193) | 1 = Poorest 2 = Poorer 3 = Middle 4 = Richer 5 = Richest | 1782 (16) 1919 (17) 2107 (19) 2495 (22) 2891 (26) |
Knowledge of Sexual and Reproductive Health Services (SRH) | 0 = No 1 = Yes | 223 (2) 10970 (98) |
Utilization of ASRH services | 0 = No 1 = Yes | 5027 (45) 6167 (55) |
Bivariate analysis:
On bivariate analysis of demographic variables with teenage pregnancy, we found that many of the variables were significant predictors of teenage pregnancy (Table 2). There was a statistically significant difference in rates of teen pregnancy based on marital status (p < 0.001) and the prevalence of teenage pregnancy was higher among married adolescents as compared to never married or divorced adolescents, with a prevalence of 90% among married participants compared to 17% of never married and 88% of divorced or separated adolescents. Teenage pregnancy was higher among adolescents who had sexual debut under the age of 16 (60%) compared with over the age of 16 (55%). 47% of teenagers with no education had teenage pregnancies, compared to 36% of those with primary education, 23% with secondary education and 12% of those with higher than secondary education, further illiterate teenagers were more likely to become pregnant than those who were able to read. Adolescents living in rural areas were more likely to have a teenage pregnancy (37%) than those living in urban areas (20%). When comparing strata of wealth index, the poorest individuals had the highest rates of teenage pregnancy. On bivariate analysis, a history of physical or sexual violence was not associated with a significant difference in teenage pregnancy between the groups.
Table 2
Analysis of intrapersonal, institutional and policy Predictors with teenage pregnancy (N = 11,194)
Variable | Characteristics | No Teenage Pregnancy (%) | Teenage Pregnancy (%) | X2 | P-value |
Marital status | 0 = never married 1 = married or cohabitating 2 = divorced or separated | 7718 (83) 171 (97) 18 (12) | 1562 (17) 1596 (90) 128 (88) | 4222.74 | < 0.001 |
Age at first cohabitation | 1 = < 16 years 2 = 16–19 years | 6.2 (20) 12 (80) | 94 (32) 88 (68) | 13.0015 | 0.03 |
Age at first sex | 1 = < 16 years 2 = 16–19 years | 1055 (40) 1125 (45) | 1613 (60) 1390 (55) | 15.21 | 0.004 |
Highest education level | 0 = No education 1 = Primary 2 = Secondary 3 = Higher than secondary | 174 (53) 3007 (64) 4690 (77) 35 (88) | 154 (47) 1715 (36) 1411 (23) 4.7 (12) | 286.83 | < 0.001 |
Employment status | 0 = Not currently working 1 = Currently working | 6839 (75) 1050 (51) | 2270 (25) 1002 (49) | 475.11 | < 0.001 |
Place of residence | 1 = urban 2 = rural | 4116 (80) 3791 (63) | 1028 (20) 2259 (37) | 414.98 | < 0.001 |
Region | 1 = Central 2 = Copperbe 3 = Eastern 4 = Luapula 5 = Lusaka 6 = Muchinga 7 = Northern 8 = North west 9 = Southern 10 = Western | 743 (69) 1581 (81) 813 (62) 561 (70) 1583 (81) 547 (71) 596 (71) 446 (63) 700 (59) 337 (57) | 333 (31) 378 (19) 489 (38) 244 (30) 376 (19) 226 (29) 240 (37) 264 (41) 487 (41) 250 (43) | 1395.64 | < 0.001 |
Literacy | 0 = Cannot read 1 = Able to read parts of sentence 2 = Able to read whole sentence | 1365 (53) 1075 (71) 5425 (77) | 1210 (47) 440 (29) 1612 (23) | 542.76 | < 0.001 |
Wealth index | 1 = Poorest 2 = Poorer 3 = Middle 4 = Richer 5 = Richest | 976 (55) 1182 (62) 1338 (63) 1799 (72) 2612 (90) | 805 (45) 737 (38) 769 (37) 696 (28) 279 (9.7) | 911.66 | < 0.001 |
Sex of household head | 1 = Male 2 = Female | 5713 (70) 2194 (73) | 2481 (30) 805 (27) | 12.76 | 0.012 |
Age of most recent partner | 1 = < 19 years 2 = 20–24 years 3 = 25–29 years 4 = 30–39 years 5 = 40–49 years | 590 (66) 667 (31) 137 (22) 13 (10) 201 (48) | 309 (34) 1472 (69) 477 (78) 110 (90) 221 (52) | 474.32 | < 0.001 |
Knowledge of Sexual and Reproductive Health Services (SRH) | 0 = No 1 = Yes | 169 (76) 7738 (71) | 55 (24) 3232 (29) | 2.74 | 0.26 |
Physical violence | 0 = No 1 = Yes | 115 (8.5) 11 (10) | 1249 (92) 97 (90) | 0.32 | 0.72 |
Sexual violence | 0 = No 1 = Yes | 114 (8.2) 12 (6.2) | 1167 (91) 179 (94) | 1.55 | 0.33 |
Utilization of ASRH services | 0 = No 1 = Yes | 4581 (91) 3327 (54) | 446 (8.9) 2840 (46) | 1896.37 | < 0.001 |
Trends in proportion of TP due to predictors of pregnancy over time:
Among adolescents with teenage pregnancies, knowledge of SRH services was significantly different by year with a chi-square of 58.02, p = 0.0014, however there was not a clear trend over time (Table 3, Fig. 1). Utilization of SRH services among teen mothers significantly increased between 2007 and 2018 with a p-value < 0.001. The prevalence of physical violence and sexual violence among adolescents with teen pregnancies was not significantly different by year, but there does appear to be a downward trend in both groups.
Table 3
Trends in proportion of TP due to Predictors of pregnancy over time
Variable | 2007 | 2014 | 2018 | X2 | P-value |
Knowledge of SRH No Yes | 3.9 (87) 443 (99) | 5.1 (48) 1041 (99.52) | 23 (2.5) 874 (97) | 58.02 | 0.0014 |
Utilization of SRH services No Yes | 178 (40) 269 (60) | 114 (11) 932 (89) | 7 (8.6) 820 (91) | 887.99 | < 0.001 |
Physical violence No Yes | 196 (91) 20 (9.1) | 428 (91) 41 (8.8) | 312 (95) 18 (5.5) | 3.84 | 0.23 |
Sexual violence No Yes | 191 (89) 25 (11) | 402 (86) 68 (14) | 287 (87) 43 (13) | 1.19 | 0.63 |
Multivariable analysis:
In model 1, we found that after adjusting for all predictors, teenage pregnancy was found to be significantly different given predictors when compared to the reference group (Table 4). In this model, the only independent factors found to be statistically significant were having a female head of house, which resulted in fewer teen pregnancies (aOR 0.25, 95% CI 0.09–0.66), sexual and reproductive health services utilization (aOR 15.98, 95% CI 6.25–40.88) and living in either central (aOR 6.37, 95% CI 1.23–33.14) or western (aOR 0.18 0.03–1.01) regions of Zambia. After adjusting for effect modification of marriage status, p-values decreased across all variables, but none became significant. When calculating goodness of fit, the F-statistic was 194.06, with a p-value < 0.001, indicating a poor fit.
Table 4
The associations between teenage pregnancy and demographic, intrapersonal, and socioeconomic factors.
| Model 1 | | | Model 1 effect modification | | | Model 2 | | | Model 2 effect mod | | | Model 3 | | | Model 3 with effect modification | | |
Variable | aOR | SE | P-value | aOR | SE | P-value | aOR | SE | P-value | aOR | SE | P-value | aOR | SE | P-value | aOR | SE | P-value |
Marital status |
Never Married | Ref | | | Ref | | | Ref | | | Ref | | | | | | 0.018 | 0.012 | < 0.001 |
Married or cohabitating | 0.903 | 0.84 | 0.913 | | | | 0.82 | 0.62 | 0.79 | 14.13 | 20.79 | 0.072 | | | | 0.047 | 0.074 | 0.05 |
Divorced or separated | 1 | | | | | | 1 | | | 1 | | | | | | 9.5E-10 | 2.40E-09 | < 0.001 |
Age at first cohabitation |
<16 years | 1.55 | 0.71 | 0.64 | 1.72 | 0.84 | 0.274 | 2.15 | 0.89 | 0.064 | 1.75E-13 | 3.83E-13 | < 0.001 | | | | | | |
16–19 years | Ref | | | Ref | | | Ref | | | Ref | | | | | | | | |
Age at first sex |
<16 years | 1.41 | 0.62 | 0.6 | 1.3 | 0.6 | 0.573 | 1.21 | 0.45 | 0.61 | 3.44E + 19 | 9.74E + 19 | < 0.001 | | | | | | |
16–19 years | Ref | | | Ref | | | Ref | | | Ref | | | | | | | | |
Sex of household head |
Male | Ref | | | Ref | | | Ref | | | Ref | | | | | | | | |
Female | 0.25 | 0.12 | 0.006 | 0.182 | 0.095 | 0.001 | 0.39 | 0.16 | 0.022 | 1.41 | 2.53 | 0.04 | | | | | | |
Age of most recent partner |
<19 years | 0.95 | 0.72 | 0.95 | 1.01 | 0.77 | 0.99 | 1.09 | 0.73 | 0.9 | 1.07 | 0.72 | 0.918 | | | | | | |
20–24 years | Ref | | | Ref | | | Ref | | | Ref | | | | | | | | |
25–29 years | 0.49 | 0.23 | 0.13 | 0.46 | 0.22 | 0.109 | 0.42 | 0.17 | 0.18 | 0.37 | 0.16 | 0.021 | | | | | | |
30–39 years | 1.97 | 1.33 | 0.314 | 2.56 | 1.82 | 0.187 | 0.91 | 0.6 | 0.88 | 3.84E-14 | 8.39E-14 | < 0.001 | | | | | | |
40–49 years | 1.39 | 1.55 | 0.77 | 1.51 | 1.64 | 0.71 | 0.86 | 0.69 | 0.85 | 0.78 | 0.64 | 0.763 | | | | | | |
Physical violence |
No | Ref | | | Ref | | | | | | | | | | | | | | |
Yes | 0.47 | 0.34 | 0.29 | 0.38 | 0.28 | 0.184 | 0.46 | 0.34 | 0.3 | 2.60E + 13 | 5.68E + 13 | < 0.001 | | | | | | |
Sexual violence |
No | Ref | | | Ref | | | | | | | | | | | | | | |
Yes | 1.83 | 1.32 | 0.4 | 2.87 | 2.13 | 0.16 | 1.82 | 1.14 | 0.34 | 7.03E-08 | 1.16E-07 | < 0.001 | | | | | | |
Highest education level |
No education | Ref | | | Ref | | | | | | | | | Ref | | | Ref | | |
Primary | 0.91 | 0.79 | 0.949 | 1.19 | 1.03 | 0.84 | | | | | | | 0.98 | 0.15 | 0.907 | 2.48 | 0.94 | 0.016 |
Secondary | 0.79 | 0.81 | 0.814 | 1.01 | 1.05 | 0.99 | | | | | | | 1.31 | 0.24 | 0.132 | 3.96 | 2.14 | 0.011 |
Higher | | | | | | | | | | | | | 1.42 | 0.99 | 0.61 | 0.53 | 0.47 | 0.476 |
Employment status |
Not working | Ref | | | Ref | | | | | | | | | Ref | | | Ref | | |
Currently working | 1.79 | 0.71 | 0.137 | 1.78 | 0.73 | 0.16 | | | | | | | 2.21 | 0.16 | 0 | 1.61 | 0.39 | 0.05 |
Place of residence | | | | | | | | | | | | | | | | | | |
Urban | Ref | | | Ref | | | | | | | | | Ref | | | Ref | | |
Rural | 0.8 | 0.44 | 0.686 | 0.74 | 0.42 | 0.56 | | | | | | | 0.8 | 0.92 | 0.05 | 0.74 | 0.23 | 0.341 |
Region | | | | | | | | | | | | | | | | | | |
Central | 6.37 | 5.35 | 0.028 | 5.74 | 4.9 | 0.04 | | | | | | | 1.01 | 0.14 | 0.95 | 0.91 | 0.4 | 0.83 |
Copperbelt | 1.98 | 1.37 | 0.323 | 1.51 | 0.99 | 0.52 | | | | | | | 0.86 | 0.13 | 0.32 | 1.37 | 0.73 | 0.556 |
Eastern | 5.72 | 5.64 | 0.078 | 4.51 | 4.35 | 0.12 | | | | | | | 0.98 | 0.14 | 0.91 | 1.13 | 0.47 | 0.78 |
Luapula | 4.25 | 5.22 | 0.24 | 3.76 | 4.92 | 0.31 | | | | | | | 0.66 | 0.1 | 0.008 | 1.47 | 0.88 | 0.52 |
Lusaka | Ref | | | Ref | | | | | | | | | Ref | | | Ref | | |
Muchinga | 1.13 | 0.84 | 0.875 | 1.18 | 0.94 | 0.83 | | | | | | | 0.7 | 0.11 | 0.023 | 1.17 | 0.54 | 0.7 |
Northern | 0.72 | 0.51 | 0.65 | 0.66 | 0.49 | 0.57 | | | | | | | 0.61 | 0.94 | 0.001 | 1.25 | 0.73 | 0.7 |
North western | 0.97 | 1.05 | 0.977 | 0.83 | 0.9 | 0.87 | | | | | | | 1.18 | 0.18 | 0.264 | 1.22 | 0.61 | 0.69 |
Southern | 1.41 | 1.1 | 0.66 | 1.48 | 1.25 | 0.65 | | | | | | | 1.45 | 0.26 | 0.038 | 1.33 | 0.67 | 0.571 |
Western | 0.18 | 0.157 | 0.052 | 0.14 | 0.14 | 0.04 | | | | | | | 1.31 | 0.2 | 0.082 | 0.39 | 0.21 | 0.09 |
Literacy | | | | | | | | | | | | | | | | | | |
Cannot read | | | | Ref | | | | | | | | | Ref | | | | | |
Able to read parts of sentence | 0.65 | 0.42 | 0.51 | 0.52 | 0.36 | 0.345 | | | | | | | 0.53 | 0.06 | < 0.001 | 0.64 | 0.24 | 0.22 |
Able to read whole sentence | 1.07 | 0.55 | 0.9 | 1.06 | 0.57 | 0.901 | | | | | | | 0.4 | 0.4 | < 0.001 | 0.65 | 0.24 | 0.24 |
Wealth index |
Poorest | 0.56 | 0.79 | 0.68 | 0.787 | 1.07 | 0.86 | | | | | | | 6.91 | 1.16 | < 0.001 | 1.53 | 0.96 | 0.5 |
Poorer | 0.35 | 0.51 | 0.47 | 0.56 | 0.81 | 0.7 | | | | | | | 5.57 | 0.89 | < 0.001 | 1.95 | 1.24 | 0.29 |
Middle | 0.15 | 0.2 | 0.152 | 0.21 | 0.27 | 0.23 | | | | | | | 5.3 | 0.8 | < 0.001 | 0.88 | 0.5 | 0.83 |
Richer | 0.091 | 0.11 | 0.056 | 0.13 | 0.16 | 0.096 | | | | | | | 3.4 | 0.46 | < 0.001 | 0.61 | 0.32 | 0.34 |
Richest | Ref | | | Ref | | | | | | | | | Ref | | | | | |
Knowledge of Sexual and Reproductive Health Services (SRH) |
No | Ref | | | Ref | | | | | | | | | | | | | | |
Yes | 0.56 | 0.58 | 0.579 | 0.68 | 0.73 | 0.72 | | | | | | | | | | | | |
Utilization of ASRH services |
No | Ref | | | Ref | | | | | | | | | | | | | | |
Yes | 15.98 | 7.64 | < 0.001 | 15.77 | 8.03 | < 0.001 | | | | | | | | | | | | |
In model 2, instead of adjusting for all variables, we adjusted for education, employment, place of residence, region, literacy status and wealth index. We found the model to be statistically significant with a p-value < 0.001. Employment status, living in a rural area, region, literacy, and wealth index were all found to significantly increase the likelihood of teenage pregnancy. Goodness of fit test resulted in an F statistic of 0.56 with a p-value of 0.811, indicating a well fit model. After effect modification with marital status, married individuals were more likely to become pregnant (aOR 34.94, 95% CI 10.18–119.93), and having secondary education became statistically significant once we adjusted for effect modification (aOR 1.79, 95% CI 1.03–3.09).
In model 3, we adjusted for intrapersonal factors of marital status, age at first marriage, age at first sex, sex of head of house, age of partner and history of physical and sexual violence. It showed that adolescents who lived in a household with a female as the head were less likely to get pregnant as compared to a male head of household. Teenage adolescents who had a partner aged 25–29 were significantly less likely to get pregnant than the reference group of 19–24 (aOR 0.42, 95% CI 0.18–0.95). Effect modification by marital status showed significant association with age at first marriage, age at first sex, partner age of 25–29 and 30–39, history of physical violence and history of sexual violence. However, goodness of fit testing had a p-value < 0.001, indicating a poor fit.