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J R Soc Med. 2001 June; 94(6): 282–285.
PMCID: PMC1281523

Design or accident? The natural history of teenage pregnancy

Clare Seamark, MPhil MRCGP

Abstract

The UK has the highest rate of teenage pregnancy in Western Europe. A retrospective record-based study was conducted in an East Devon general practice to gain greater understanding of the outcome of first teenage pregnancy and subsequent reproductive history. The comparison group was women who had first conceived between the ages of 25 and 29 years.

149/673 women born between 1968 and 1977 became pregnant when teenagers. Of these, 70 (47%) had the baby, 67 (45%) had a termination and 10 (7%) had a spontaneous miscarriage; 2 others experienced fetal loss. Of the women aged 25-29 at first conception, 127 (92%) had the baby, 6 (4%) had a termination and 5 (4%) had a miscarriage. 40 (27%) of the teenage group went on to have a second teenage pregnancy, including 12 of the 67 who had their first pregnancy terminated.

Although teenage pregnancy is often viewed as unplanned and unwanted, the reality is more complex. Among this group, many first pregnancies were desired. Even among those whose first pregnancy was terminated, 18% went on to have a baby while still a teenager.

INTRODUCTION

Teenage pregnancy is a cause for concern in the UK, and halving of the rate in under-16s is an unmet target of The Health of the Nation1. It is also the subject of a recent report from the Social Exclusion Unit2. However, there is still much we do not know or understand about the subject. Although the UK does have the highest rate of teenage pregnancy in Western Europe, the rate was even higher in the past3,4. In England and Wales at least 94 377 teenagers became pregnant in 1996 and 38% of these pregnancies were terminated4. Miscarriage is not included in the nationally collected data, which concentrate on conceptions leading to maternities and terminations of pregnancy. Very little is known about what happens after the first teenage pregnancy. Was it an isolated event or the beginning of a complex reproductive history?

East Devon has a relatively low rate of teenage pregnancy—5.3 per 1000 women under 16 years, compared with 9.4 per 1000 for England and Wales in 19964. Nevertheless, at least 1 in 5 women born between 1955 and 1977 and registered with our Honiton Practice were to experience a teenage pregnancy.

This new study seeks to look at teenage pregnancy from a primary care perspective. The advantages are that all pregnancies, including miscarriages, can be studied, women can be followed up for repeat pregnancies and women from different age groups can be compared.

METHODS

The study was conducted in the Honiton Group Practice, which serves a population of 15 300 in the East Devon market town and surrounding rural area. The Townsend score of the town varies from -1 to +1. The study is part of a larger research project on teenage pregnancy, which has received ethical approval.

The practice uses the Exeter Computer System and has been fully computerized since 1990. All consultations and significant events, such as pregnancies, are recorded. The database was searched for women born between 1968 and 1977 who were registered on 1 January 1998 and were still registered at the end of 1999. The records of these women were searched to see if they had had a teenage pregnancy, for the outcome of such pregnancies and for subsequent reproductive histories.

The practice database was also searched for women who had conceived when aged between 25 and 29 years and completed their first pregnancy by the end of 1997. The outcome of these pregnancies and follow-up over at least 2 years was also recorded.

RESULTS

First pregnancies

Of 638 women in the teenage study group, 149 had experienced at least one teenage pregnancy. The age at conception and the outcome of these first pregnancies are contrasted in Table 1 with data for women aged 25-29. Only 14 girls conceived before the age of 16 (9% of teenage pregnancies). Younger teenagers are more likely to have a termination (83% of 15-year-olds) than older teenagers (34% of 19-year-olds). Over 95% presented within the first trimester. 2 girls concealed their pregnancies until 28 weeks and term, respectively. 2 babies were adopted—one with a teenage mother, the other with a mother aged 29.

Table 1
Outcome of pregnancies for teenagers and women aged 25-29 years

Subsequent reproductive history

By the end of 1999, when the teenage pregnancy group were aged 22-31 years, 108 (73%) had had a second pregnancy, 40 (27%) when still teenagers. Of those whose first pregnancy resulted in a baby 54/70 (77%) became pregnant again. Table 2 shows the gaps between end of first pregnancy and next conception in the two groups of women. In both groups the gap tended to be longest among those whose first pregnancies were terminated. Of the women whose first teenage pregnancy resulted in a baby, 46% were pregnant again within 2 years compared with 27% of those who had a termination first.

Table 2
Gap between end of last pregnancy and next conception in teenagers and women aged 25-29

Of the 40 women who became pregnant a second time as teenagers, 28 had the baby, 6 had a termination and 6 miscarried. A total of 88 girls (59%) had babies as teenagers despite 12 of their first pregnancies (and in 2 cases first and second pregnancies) being terminated and 6 first pregnancies ending in miscarriage or fetal loss.

Of the 41 women who had had only one pregnancy by the end of 1999, 3 miscarried the first pregnancy and one is now trying to become pregnant by use of in-vitro fertilization; 16 have one child and 22 had one termination.

Amongst these 149 women there have been a total to date of 351 pregnancies. These have resulted in 92 terminations, 227 babies (including one set of twins), 1 stillbirth, 2 intrauterine deaths, 2 medical terminations for fetal abnormality and 28 miscarriages. By the end of 1999, 118/149 (79%) had at least one baby (range of 1-4) and 77/149 (52%) women had had at least one termination of pregnancy, 13 two terminations and one three. 24 (16%) women had experienced spontaneous miscarriage, 4 having had two miscarriages.

One woman had been referred to a fertility clinic after trying to conceive for over 3 years. She actually conceived at the age of 19.9 years just before attending. 3 women experienced secondary fertility problems.

Among women aged 25-29 years at first conception, 85/138 (62%) had a second pregnancy. The gaps are shown in Table 2. By the end of 1999 these women had had a total of 248 pregnancies, median 2 (range 1-5). 9 women had had difficulty conceiving and one had used clomiphene, one in-vitro fertilization and one artificial insemination by donor to conceive.

The teenagers who had a baby from their first conception were more likely to get pregnant again than women in the 25-29 year group (χ2 with Yates correction =4.81, P<0.05). The teenagers who had a termination first were not significantly more likely to get pregnant again than the older women. In each group the median number of pregnancies at the end of the study was 2, range 1-6 in the teenagers, 1-5 in the older women.

DISCUSSION

Although the teenage pregnancy rate in East Devon is well below the national average, 1 in 5 girls still conceive as teenagers. Of the teenage pregnancies recorded in this study, half were terminated, with highest termination rates in the very young. Over a quarter of the girls went on to have further teenage pregnancies, including 18% of those who had their first pregnancy terminated; but those whose first pregnancies were terminated tended to wait longer before becoming pregnant again than those who kept their babies. At the close of the study, the median number of pregnancies in the teenage group did not differ from that in the group who first became pregnant at age 25-29.

The strengths of this study come from the comprehensive nature of the computerized general practice record. Pregnancies were unlikely to be missed, and the follow-up data in this population are good. However, the results may not be typical of the rest of the country for several reasons. First, termination of pregnancy is readily available in East Devon, 95% being provided by the National Health Service; the 49% termination rate in our teenage group must be compared with 38% for England and Wales4. Other workers have reported highest termination rates in affluent areas and where the overall pregnancy rate is low5. Moreover, we already know that high teenage pregnancy rates are associated with low socioeconomic status5,6,7, with maternal history of teenage conception8,9, with poor educational achievement and with family disruption6,7, none which could be adjusted for here.

The findings in this study suggest that many of the teenagers became pregnant by design rather than by accident. In the UK, the Social Exclusion Unit report stated that about 10% of 16-19-year-olds whose pregnancy is terminated have already undergone one abortion and 2% have had both an abortion and a baby2. A study in East Anglia of pregnant girls aged 13-16 indicated that 11/98 (12%) had been pregnant before6. In the United States researchers have tended to focus on girls whose first pregnancy produced a baby, and some 30-50% conceived again within 24 months10. The corresponding figure in Honiton was 46%.

Can we identify the individuals most likely to have a rapid repeat pregnancy? Suggested risk factors include young age at first pregnancy, low socioeconomic status, low educational achievement in the teenager and head of household, married status, intended or desired first pregnancy, and use of contraception other than Norplant11. But there is no consensus. In one American study the main risk factor seemed to be a lack of motivation not to have a second pregnancy12. Second pregnancies in American teenagers are more likely to be desired than first pregnancies. This seems to be true also in Honiton, even though a rapid repeat pregnancy is associated with negative short-term consequences in terms of education, employment and welfare dependency. Those whose first pregnancy produced a baby were particularly likely to become pregnant again as teenagers.

In the 1970s it was observed that women who started childbearing in their teens had more children, closer together, than women who delayed childbearing13. This we have not yet found in Honiton, though the younger group in our study still have many remaining years of fertility.

Acknowledgments

Thanks are due to the partners and staff of the Honiton Group Practice, especially Dr David Seamark. The author received the 1998-2000 Research Training Fellowship from the RCGP/BUPA. The Honiton Group Practice is a NHS Funded Research Practice.

References

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2. Social Exclusion Unit. Teenage pregnancy. London: Stationery Office, 1999
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Articles from Journal of the Royal Society of Medicine are provided here courtesy of Royal Society of Medicine Press