Table 2.
Characteristics of women aged 18–24 years in England in Natsal-2 and Natsal-3 and factors associated with conception in women younger than 18 years
|
1999–2001 |
2010–12 |
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Number of participants (unweighted, weighted) | Percentage of participants with characteristic* | Percentage who had conception at age <18 years (95% CI) | OR for <18 years conception |
Number of participants (unweighted, weighted) | Percentage of participants with characteristic* | Percentage who had conception at age <18 years (95% CI) | OR for <18 years conception |
||||||
| OR | AOR (95% CI) | p value | OR | AOR (95% CI) | p value | ||||||||
| Total <18 years conception prevalence | 967, 993 | .. | 13% (10·8–15·6) | .. | .. | .. | 1368, 817 | .. | 11% (9·1–12·4) | .. | .. | .. | |
| Area-level deprivation | 0·008 | 0·005 | |||||||||||
| 1 (least deprived) | 113, 115 | 12% | 3% (1·3–8·5) | 1 | 1 | .. | 219, 131 | 16% | 6% (3·1–9·9) | 1 | 1 | .. | |
| 2 | 115, 124 | 12% | 10% (5·3–18·4) | 3·23 | 3·4 (0·98–11·77) | .. | 227, 133 | 16% | 8% (5·0–11·3) | 1·37 | 1·18 (0·51–2·74) | .. | |
| 3 | 137, 156 | 16% | 8% (4·7–13·7) | 2·56 | 2·2 (0·78–6·22) | .. | 259, 164 | 20% | 7% (4·4–10·7) | 1·25 | 1·37 (0·55–3·39) | .. | |
| 4 | 229, 256 | 26% | 14% (9·5–19·3) | 4·58 | 3·48 (1·22–9·97) | .. | 307, 194 | 24% | 13% (9·4–16·8) | 2·43 | 2·15 (0·94–4·89) | .. | |
| 5 (most deprived) | 373, 342 | 34% | 19% (14·7–24·3) | 6·82 | 5·18 (1·91–14·05) | .. | 356, 195 | 24% | 17% (13·5–21·8) | 3·51 | 2·89 (1·25–6·67) | .. | |
| Quintiles of baseline teenage pregnancy rate | 0·387 | 0·3182 | |||||||||||
| 1 (low) | 176, 203 | 21% | 11% (7·1–16·6) | 1 | 1 | .. | 249, 154 | 19% | 8% (5·5–12·4) | 1 | 1 | .. | |
| 2 | 190, 188 | 19% | 12% (7·7–18·7) | 1·12 | 0·79 (0·34–1·80) | .. | 252, 139 | 17% | 14% (10·1–18·4) | 1·75 | 1·16 (0·58–2·31) | .. | |
| 3 | 211, 211 | 21% | 15% (10·6–21·5) | 1·47 | 0·83 (0·38–1·80) | .. | 242, 134 | 16% | 10% (6·9–15·0) | 1·26 | 0·72 (0·33–1·60) | .. | |
| 4 | 216, 252 | 25% | 14% (8·8–20·7) | 1·29 | 1·04 (0·50–2·18) | .. | 304, 185 | 23% | 10% (7·4–14·1) | 1·26 | 0·66 (0·32–1·36) | .. | |
| 5 (high) | 171, 136 | 14% | 11% (6·9–18·1) | 1·04 | 0·52 (0·23–1·18) | .. | 320, 204 | 25% | 11% (7·8–15·0) | 1·35 | 0·67 (0·31–1·43) | .. | |
| Academic qualifications in participants ≥17 years | <0·0001 | <0·0001 | |||||||||||
| Studying/gained further qualifications | 435, 475 | 50% | 4% (2·1–5·9) | 1 | 1 | .. | 825, 523 | 66% | 5% (3·4–6·1) | 1 | 1 | .. | |
| None, or those typically gained at 16 years† | 500, 483 | 50% | 23% (19·1–27·1) | 7·99 | 5·61 (2·97–10·62) | .. | 510, 266 | 34% | 23% (19·4–27·0) | 6·24 | 3·61 (2·29–5·67) | .. | |
| Heterosexual intercourse before age 16 years | <0·0001 | <0·0001 | |||||||||||
| No | 693, 713 | 72% | 7% (4·8–9·0) | 1 | 1 | .. | 884, 564 | 71% | 5% (4·1–7·0) | 1 | 1 | .. | |
| Yes | 270, 274 | 28% | 29% (24·0–35·3) | 5·86 | 3·33 (2·04–5·45) | .. | 452, 233 | 29% | 24% (20·2–28·6) | 5·63 | 3·2 (2·03–5·04) | .. | |
| Reliable contraception used at first sex‡ | 0·0032 | 0·1906 | |||||||||||
| Yes | 701, 724 | 82% | 12% (9·4–14·7) | 1 | 1 | .. | 990, 584 | 87% | 11% (9·0–12·9) | 1 | 1 | .. | |
| No | 163, 156 | 18% | 27% (19·7–35·3) | 2·73 | 2·09 (1·28–3·40) | .. | 160, 87 | 13% | 22% (16·2–28·8) | 2·3 | 1·44 (0·83–2·48) | .. | |
| View on timing of first sex | 0·079 | 0·0693 | |||||||||||
| About the right time/too late | 508, 520 | 59% | 10% (7·4–13·4) | 1 | 1 | .. | 726, 439 | 65% | 9% (7·2–11·4) | 1 | 1 | .. | |
| Too early | 353, 357 | 41% | 21% (16·9–25·9) | 2·39 | 1·6 (0·95–2·70) | .. | 426, 232 | 35% | 18% (15·0–22·4) | 2·26 | 1·56 (0·96–2·52) | .. | |
| Main reason for first sex | 0·1782 | 0·7324 | |||||||||||
| Autonomous reason | 713, 723 | 85% | 14% (11·8–17·5) | 1 | 1 | .. | 932, 551 | 83% | 11% (9·5–13·6) | 1 | 1 | .. | |
| Non-autonomous reason§ | 128, 130 | 15% | 15% (9·4–22·1) | 1·01 | 0·58 (0·26–1·29) | .. | 205, 111 | 17% | 17% (12·6–23·6) | 1·64 | 1·09 (0·66–1·81) | .. | |
| Partner more willing at first sex | 0·356 | 0·1182 | |||||||||||
| No | 650, 673 | 77% | 13% (10·4–15·8) | 1 | 1 | .. | 970, 564 | 83% | 12% (10·4–14·6) | 1 | 1 | .. | |
| Yes | 211, 204 | 23% | 20% (14·7–26·7) | 1·7 | 1·27 (0·76–2·13) | .. | 203, 118 | 17% | 14% (9·5–19·0) | 1·12 | 0·62 (0·33–1·13) | .. | |
| Sex education source | 0·2297 | 0·0478 | |||||||||||
| School lessons | 253, 281 | 29% | 9% (5·4–13·7) | 1 | 1 | .. | 519, 314 | 38% | 8% (6·0–10·3) | 1 | 1 | .. | |
| Parents | 180, 193 | 20% | 13% (8·4–18·5) | 1·51 | 1·73 (0·75–3·99) | .. | 205, 119 | 15% | 11% (7·3–15·4) | 1·4 | 1·01 (0·48–2·11) | .. | |
| Other | 518, 502 | 51% | 16% (12·7–19·7) | 1·99 | 1·69 (0·92–3·10) | .. | 639, 383 | 47% | 13% (10·3–15·7) | 1·71 | 1·71 (1·06–2·75) | .. | |
| Needed more information at first sex | 0·1033 | 0·3937 | |||||||||||
| No | 223, 232 | 24% | 7% (4·1–11·8) | 1 | 1 | .. | 331, 207 | 28% | 8% (5·9–11·6) | 1 | 1 | .. | |
| Yes | 711, 727 | 76% | 15% (12·7–18·7) | 2·43 | 1·79 (0·89–3·61) | .. | 930, 535 | 72% | 12% (10·4–14·7) | 1·56 | 1·25 (0·75–2·10) | .. | |
| Communication with parents about sex | 0·5468 | 0·9317 | |||||||||||
| Easy | 328, 349 | 36% | 12% (8·4–16·4) | 1 | 1 | .. | 428, 256 | 32% | 10% (7·6–13·4) | 1 | 1 | .. | |
| Difficult/not discussed/varied | 616, 626 | 64% | 13% (10·3–16·5) | 1·12 | 1·22 (0·64–2·31) | .. | 896, 543 | 68% | 10% (8·1–12·1) | 0·98 | 0·98 (0·58–1·65) | .. | |
| Lived with both natural parents¶ | 0·2437 | 0·0088 | |||||||||||
| Yes | 683, 714 | 72% | 11% (8·2–13·4) | 1 | 1 | .. | 826, 527 | 65% | 7% (5·2–8·6) | 1 | 1 | .. | |
| No | 284, 279 | 28% | 19% (15·0–24·6) | 2·04 | 1·31 (0·83–2·08) | .. | 541, 289 | 35% | 18% (14·8–21·3) | 3·02 | 1·72 (1·15–2·57) | .. | |
Conception before age 18 years was classified as livebirths occurring before age 18 years 9 months and abortions occurring at age 17 years and younger. Miscarriages were excluded because of common misreporting, in common with Office of National Statistics. Stillbirths excluded for comparability between Natsal-2 and Natsal-3. OR=odds ratio. AOR=adjusted odds ratio.
Percentages were calculated for weighted participants.
English General Certificate of Secondary Education or equivalent.
Contraceptive pill or condom.
Non-autonomous reason for first sex defined as copying peers or being under the influence of alcohol in Natsal-2 and copying peers or being under the influence of alcohol or recreational drugs in Natsal-3.
Until age 14 years in Natsal-2 and until age 16 years in Natsal-3. AOR is adjusted for whether participants lived with both natural parents until age 14 years or 16 years, ease of communication with parents about sex, Index of Multiple Deprivation, educational attainment, main source of sex education, whether more information was needed at first sex, contraceptive method use at first sex, whether both partners were equally willing at first sex, autonomy of the reason for first sex, and baseline conception rate at younger than 18 years (area-level), but not adjusted for first sex before age 16 years.