Volume 94, Issue 11 p. 1175-1180
Original Research Article
Free Access

Characteristics of women with repeat termination of pregnancy: a study of all requests for pregnancy termination in Norway during 2007–2011

Ragnhild T. Justad-Berg

Corresponding Author

Ragnhild T. Justad-Berg

Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway

Institute of Clinical Medicine, University of Oslo, Oslo, Norway

Correspondence

Ragnhild T. Justad-Berg, Department of Obstetrics and Gynecology, Akershus University Hospital, 1478 Lørenskog, Norway.

E-mail: [email protected]

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Anne Eskild

Anne Eskild

Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway

Institute of Clinical Medicine, University of Oslo, Oslo, Norway

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Ellen M. Strøm-Roum

Ellen M. Strøm-Roum

Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway

Institute of Clinical Medicine, University of Oslo, Oslo, Norway

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First published: 28 July 2015
Citations: 18
This study has used data from the Medical Birth Registry of Norway. The interpretation and reporting of these data is the sole responsibility of the authors, and no endorsement by the Medical Birth Registry of Norway is intended nor should be inferred. The authors have no conflicts of interest to declare.

Abstract

Introduction

We studied the proportion of all pregnancy terminations requested by women with a history of pregnancy termination. We also studied risk factors for repeat pregnancy termination.

Material and methods

We used data from the Norwegian Register of Pregnancy Termination during the period 2007–2011, a total of 80 346 requests for pregnancy termination before the end of the 12th gestational week. Odds ratios for repeat pregnancy termination were estimated according to age, parity, contraceptive use, marital status, education, employment status and region of residency by applying logistic regression analyses. Repeat pregnancy termination was defined as request for pregnancy termination for the second time or more.

Results

Among the 80 346 requests for pregnancy termination, 36.7% were among women with a history of pregnancy termination. In total, 25.0% had one prior termination and 11.7% had two or more. Factors associated with repeat pregnancy termination were; age ≥25 years, having one or more children, and use of contraception at the time of conception. College/university education as compared with primary school only, was associated with reduced risk of repeat termination.

Conclusion

Among all requests for pregnancy termination in Norway, 36.7% were from women with a history of pregnancy termination. Many women with repeat pregnancy termination have children and/or used contraception at the time of conception. Our findings therefore suggest that high fecundity is an underlying risk factor for repeat pregnancy termination.

Abbreviations

  • aOR
  • adjusted odds ratio
  • CI
  • confidence interval
  • OR
  • odds ratio
  • SD
  • standard deviation
  • Key Message

    Repeat pregnancy termination is associated with higher age, previous childbirth and use of contraception at the time of conception.

    Introduction

    Unwanted pregnancies and pregnancy terminations are important public health issues worldwide. To develop targeted prevention programs and to improve individual counseling on family planning, increased knowledge about risk factors for pregnancy termination is necessary 1. However, population-based studies on risk factors for pregnancy termination barely exist. One reason for this is the lack of systematic registration of pregnancy terminations in most countries.

    A large proportion of all pregnancy terminations are possibly performed among women with a history of pregnancy termination. In Sweden in 2011, 41% of all pregnancy terminations were performed in women with one or more prior terminations 2. In Finland and England and Wales, the proportions of women with repeat termination of pregnancy have been estimated to be between 30 and 40%, and in the USA the proportion may be as high as 48% 3-5.

    The characteristics of women with repeat pregnancy termination are not well known. In previous studies performed in Europe, USA and Canada, repeat pregnancy termination has been related to both low and high age 5-9. Other risk factors have also been identified; e.g. having children, being unmarried, low socioeconomic status, low educational level, use of oral contraceptives, smoking cigarettes, history of physical or sexual abuse and alcohol/drug abuse 5-10. However, none of these studies included women from an entire country, and in most studies the independent associations of the different risk factors with repeat pregnancy termination were not reported.

    To gain further insight into the prevalence and risk factors of repeat pregnancy termination, we studied all requests for pregnancy termination in Norway during 2007–2011. We estimated the proportion of requests among women with a history of pregnancy termination. We also examined whether age, previous childbirth, contraceptive use, marital status, educational level, employment status or region of residency was associated with repeat pregnancy termination.

    Material and methods

    Pregnancy termination before the 12th gestational week at the woman's request has been legal in Norway since 1979 11. All pregnancy terminations in Norway are performed, or the treatment initiated, in public hospitals. Pregnancy terminations are financed through the Norwegian welfare system and are free of charge.

    We used data from the Norwegian Register of Pregnancy Termination to which all requests for pregnancy termination are reported by law. The register was established in 1979 and has been maintained as an electronic register by the Norwegian Institute of Public Health since 2006 12. Information on individual women who request pregnancy termination is anonymized, but the reporting includes information about the women's reproductive history and socio-demographic status. The data are obtained by a standardized patient record completed by the physician at the clinical examination of the women prior to the pregnancy termination 13.

    We excluded all requests for pregnancy termination during 2006 since a large proportion of these requests lacked information about prior pregnancy termination. Thus, our study included all requests for pregnancy termination before the end of the 12th gestational week in Norway during 2007–2011, a total of 80 346 requests. Our outcome variable was prior pregnancy termination (0, 1 or ≥2 prior pregnancy terminations or missing information). We used the following explanatory variables; age (5-year intervals, reference 20–24 years), parity [0 (reference), 1 or ≥2 childbirths after the 22nd gestational week or missing information], contraceptive use at the time of conception [no use (reference), withdrawal/rhythm method, condom, hormonal contraception/intrauterine contraceptive device, male/female sterilization, emergency contraception, other or missing information], marital status [married/cohabiting (reference), single, divorced/widow or missing information], education [primary school (reference), upper secondary school, college/university or missing information], employment status [full-time/part-time employment (reference), student, student with employment, unemployed/on welfare program or missing information] and region of residency [east (reference), Oslo (capital), south, west, mid, north or missing information].

    Statistical analysis

    We estimated the proportions of all requests for pregnancy termination among women with no, one, or two or more prior pregnancy terminations. We also studied the distribution of each study factor according to number of prior pregnancy terminations, and differences were tested by applying the chi-squared test. Logistic regression analyses were used to estimate crude and adjusted odds ratios (OR, aOR) with 95% confidence intervals (CI) for having repeat pregnancy termination according to the explanatory variables listed above. In these analyses, repeat pregnancy termination was defined as request for pregnancy termination for the second time or more (yes/no). We used SPSS version 21.0 for Windows (IBM Corp., Armonk, NY, USA) for the statistical analyses.

    The study was approved by the Advisory Committee for the Medical Birth Registry of Norway (reference number: MFR 12-1555) and the Data Inspectorate of Norway (reference number: 62982).

    Results

    In the study population as a whole, the mean age was 27.6 years [standard deviation (SD) 7.1 years] and 53.1% reported one or more previous childbirths (Table 1).

    Table 1. Distribution of study factors according to number of prior pregnancy terminations among 80 346 requests for pregnancy termination in Norway during 2007–2011
    Total Number of prior pregnancy terminations
    0 1 ≥2 Missing
    n % n % n % n % n %
    Age, years
    ≤19 10 038 12.5 8063 17.3 1112 5.5 196 2.1 667 15.7
    20–24 22 743 28.3 14 401 30.9 5326 26.6 1835 19.5 1181 27.8
    25–29 17 850 22.2 9380 20.1 4944 24.6 2594 27.5 932 21.9
    30–34 13 740 17.1 6849 14.7 4040 20.1 2210 23.5 641 15.1
    35–39 10 765 13.4 5330 11.4 3153 15.7 1744 18.5 538 12.7
    40–44 4733 5.9 2340 5.0 1348 6.7 785 8.3 260 6.1
    ≥45 477 0.6 248 0.5 137 0.7 59 0.6 33 0.7
    Previous childbirth
    0 37 718 46.9 26 715 57.3 8026 40.0 2814 29.9 163 3.8
    1 15 085 18.8 7638 16.4 4759 23.7 2481 26.3 207 4.9
    ≥2 23 719 29.5 12 216 26.2 7093 35.4 4067 43.2 343 8.1
    Missing 3824 4.8 42 0.1 182 0.9 61 0.6 3539 83.2
    Use of contraception
    None 51 041 63.5 30 872 66.2 12 004 59.8 5769 61.2 2396 56.3
    Withdrawal/rhythm method 643 0.8 362 0.8 166 0.8 79 0.8 36 0.8
    Condom 8852 11.0 4952 10.6 2341 11.7 1003 10.6 556 13.1
    Hormonal/intrauterine 15 604 19.4 8146 17.5 4492 22.4 2087 22.1 879 20.7
    Male/female sterilization 199 0.2 99 0.2 63 0.3 24 0.3 13 0.3
    Emergency contraception 1273 1.6 676 1.5 346 1.7 186 2.0 65 1.5
    Other 1197 1.5 780 1.7 282 1.4 89 0.9 46 1.1
    Missing 1537 1.9 724 1.6 366 1.8 186 2.0 261 6.1
    Marital status
    Married/cohabitant 35 300 49.3 19 849 42.6 9317 46.4 4273 45.3 1861 43.8
    Single 37 849 47.1 22 678 48.7 8944 44.6 4288 45.5 1939 45.6
    Divorced/widow 3549 4.4 1908 4.1 1013 5.0 515 5.5 113 2.7
    Missing 3648 4.5 2176 4.7 786 3.9 347 3.7 339 8.0
    Education
    Primary school 15 038 18.7 9026 19.4 3380 16.8 1896 20.1 736 17.3
    Upper secondary school 34 775 43.3 19 668 42.2 9023 45.0 4281 45.4 1803 42.4
    College/university 18 292 22.8 10 828 23.2 4773 23.8 1790 19.0 901 21.2
    Missing 12 241 15.2 7089 15.2 2884 14.4 1456 15.5 812 19.1
    Employment status
    Full-time or part-time 42 545 53.0 23 586 50.6 11 632 58.0 5305 56.3 2022 47.6
    Student 16 299 20.3 11 203 24.0 2968 14.8 1083 11.5 1045 24.6
    Student with employment 1924 2.4 1263 2.7 460 2.3 158 1.7 43 1.0
    Unemployed/welfare program 12 920 16.1 6707 14.4 4337 17.2 2181 23.1 585 13.8
    Missing 6658 8.3 3852 8.3 1553 7.7 696 7.4 557 13.1
    Region of residency
    East 18 512 23.0 11 125 23.9 4673 23.3 2325 24.7 389 9.1
    Oslo (capital) 15 508 19.3 8875 19.0 4324 21.6 2232 23.7 77 1.8
    South 13 850 17.2 8274 17.8 3541 17.7 1490 15.8 545 12.8
    West 13 809 17.2 9013 19.3 3255 16.2 1343 14.3 198 4.7
    Mid 9906 12.3 4472 9.6 2040 10.2 897 9.5 2497 58.7
    North 8386 10.4 4621 9.9 2138 10.7 1092 11.6 535 12.6
    Missing 373 0.5 231 0.5 88 0.4 43 0.5 11 0.3

    Of the 80 346 requests for pregnancy termination, 36.7% (= 29 483) were among women with a history of pregnancy termination; 25.0% (= 20 060) among women with one prior termination, and 11.7% (n = 9423) among women with two or more prior terminations. For 5.3% (n = 4252) of the requests, information about prior pregnancy termination was missing.

    Women <25 years old represented 40.8% (n = 32 781) of all requests for pregnancy termination (Figure 1, Table 1), 32.1% (n = 6438) of women with one prior pregnancy termination, and 21.6% (n = 2031) of women with two or more prior terminations. In comparison, women 35–44 years old represented 19.3% (n = 15 498) of all requests for pregnancy termination, 22.4% (n = 4501) of women with one prior termination, and 26.8% (n = 2529) of women with two or more terminations.

    Details are in the caption following the image
    Age distribution among women requesting pregnancy termination in Norway during 2007–2011 (n = 80 346), according to number of prior pregnancy terminations.

    The crude OR for having a repeat pregnancy termination was reduced for women less than 20 years old and increased for all age groups above 25 years old (Table 2) as compared with women 20–24 years old. In these analyses, we excluded all requests with missing information on history of pregnancy termination, and a total of 76 094 requests were included. Adjustments for the other study factors did not significantly alter the ORs for repeat pregnancy termination associated with age. Thus, as compared with women 20–24 years old, the aOR for repeat pregnancy termination was 1.61 (95% CI 1.54–1.68) for women 25–29 years old, and 1.79 (95% CI 1.70–1.89) for women 30–34 years old. There was no further increase in the aORs for women 35 years or older. The aOR for women <20 years old was 0.35 (95% CI 0.32–0.37).

    Table 2. Crude and adjusted (a) odds ratios (OR) with 95% confidence intervals (CI) for repeat pregnancy termination. All requests for pregnancy termination in Norway during 2007–2011 with information about prior pregnancy termination are included in the data analyses (n = 76 094)
    OR 95% CI aORa 95% CI aORb 95% CI
    Age, years
    ≤19 0.33 0.31–0.35 0.35 0.32–0.37
    20–24 ref ref
    25–29 1.62 1.55–1.69 1.61 1.54–1.68
    30–34 1.84 1.76–1.92 1.79 1.70–1.89
    35–39 1.85 1.76–1.94 1.83 1.72–1.94
    40–44 1.83 1.72–1.96 1.85 1.71–1.99
    ≥45 1.59 1.32–1.92 1.64 1.35–2.00
    Previous childbirth
    0 ref ref ref
    1 2.34 2.25–2.43 1.91 1.83–1.99 1.72 1.65–1.80
    ≥2 2.25 2.18–2.33 1.48 1.42–1.55 1.51 1.44–1.58
    Use of contraception
    None ref ref ref
    Withdrawal/rhythm method 1.18 1.00–1.38 0.93 0.79–1.10 1.08 0.91–1.27
    Condom 1.17 1.12–1.23 1.16 1.10–1.21 1.26 1.20–1.32
    Hormonal/intrauterine 1.40 1.35–1.46 1.60 1.54–1.67 1.67 1.61–1.74
    Male/female sterilization 1.53 1.16–2.04 0.97 0.73–1.30 1.20 0.90–1.61
    Emergency contraception 1.37 1.22–1.53 1.42 1.27–1.60 1.46 1.30–1.65
    Other 0.83 0.73–0.94 0.82 0.72–0.93 0.96 0.84–1.10
    Marital status
    Married/cohabitant ref ref ref
    Single 0.85 0.83–0.88 1.14 1.10–1.18 1.31 1.26–1.35
    Divorced/widow 1.17 1.09–1.26 1.06 0.99–1.14 1.10 1.02–1.18
    Education
    Primary school ref ref ref
    Upper secondary school 1.16 1.11–1.21 1.01 0.97–1.05 0.86 0.83–0.90
    College/university 1.04 0.99–1.09 0.65 0.62–0.68 0.58 0.55–0.61
    Employment status
    Full–time/part–time ref ref ref
    Student 0.50 0.48–0.53 0.71 0.68–0.74 0.80 0.77–0.84
    Student with employment 0.68 0.62–0.75 0.89 0.81–0.99 0.97 0.88–1.08
    Unemployed/welfare program 1.17 1.12–1.22 1.24 1.19–1.30 1.09 1.04–1.14
    Region of residency
    East ref ref ref
    Oslo (capital) 1.17 1.12–1.23 1.17 1.12–1.23 1.28 1.23–1.35
    South 0.97 0.92–1.01 1.02 0.97–1.07 0.97 0.93–1.02
    West 0.81 0.77–0.85 0.85 0.81–0.89 0.82 0.78–0.86
    Mid 1.04 0.99–1.10 1.10 1.04–1.17 0.99 0.94–1.05
    North 1.11 1.05–1.17 1.21 1.15–1.28 1.20 1.13–1.27
    • a Adjustment made for age only.
    • b Mutual adjustments made for age, previous childbirth, contraceptive use, marital status, education, employment status and region of residency.

    Women with a previous childbirth, women who had used contraception at the time of conception or were single, had an increased risk for repeat pregnancy termination, whereas women with high education had a reduced risk. Women with residency in Oslo or in the north of Norway had an increased risk for repeat pregnancy termination (Table 2).

    We repeated the analyses for women <25 years old and ≥25 years old, and the estimated associations were similar in both groups (data not shown). However, the association of previous childbirth with repeat pregnancy termination was stronger in women <25 years than in women ≥25 years old, with an aOR of 1.82 (95% CI 1.69–1.96) and an aOR of 1.64 (95% CI 1.55–1.74), respectively.

    Discussion

    This study included all requests for pregnancy termination in Norway during the period 2007–2011, and 36.7% of the requests were from women with a history of pregnancy termination. Women aged ≥25 years, women with a previous childbirth and women who had used contraception at the time of conception were at increased risk of repeat pregnancy termination. High educational levels were associated with a reduced risk.

    Since we included all requests for pregnancy termination in Norway during the study period, skewed sampling is not a source of bias. Also, the large sample provides statistical power. We are not aware of any previous study on repeat pregnancy termination that has used data from a country as a whole.

    All requests for pregnancy termination after the 12th gestational week were excluded since these pregnancy terminations are not performed at the women's request only but may be performed after approval by the hospital's pregnancy termination board. According to the Norwegian Act on pregnancy termination, the reasons that allow termination after the 12th gestational week are serious offspring birth defects or difficult social and/or health conditions for the woman 11. Approximately 4% of all pregnancy terminations in Norway are performed after the 12th gestational week 14.

    When estimating odds ratios for repeat pregnancy termination, we excluded all requests that lacked information about prior pregnancy termination(s) (5% of total). The age distribution of the women with excluded requests was similar to those who were included. Therefore, we do not believe that our estimates of the association of age with repeat pregnancy termination are biased.

    The time since the prior pregnancy termination is not reported to the Register of Pregnancy Termination. Also, information on ethnicity, income and religion is lacking. Thus, these factors could not be studied. Use of contraception at the time of conception may be erroneously reported or contraception may have been erroneously used. We do not know whether women with a prior pregnancy termination are more likely to erroneously report contraceptive use than women without such a history. The women in our study were anonymized, and we could therefore not identify the reproductive history for individual women. However, the number of prior pregnancy terminations was reported for each request in the standardized patient record. Thus, we do not consider the proportion of women with repeat termination of pregnancy to be biased information. In our study, we did not aim at studying lifetime risk of pregnancy terminations.

    According to reports from Sweden, Finland, the USA and England and Wales, from a third and up to half of all pregnancy terminations are performed in women with one or more prior terminations 2-5. In a previous Norwegian study, 16% of the women who requested pregnancy termination had had a prior termination. That study was performed during 1972–81 and included all pregnancy terminations in six of the 19 Norwegian counties 15. Thus, it is possible that the prevalence of repeat termination of pregnancy has more than doubled over a 30-year period.

    Previous studies on risk factors for repeat pregnancy termination are scarce, and prior study samples may not have included all women who requested termination of pregnancy 5-10. However, findings from some of these studies are similar to ours and suggest that the risk of repeat pregnancy termination is associated with high age, previous childbirth, use of oral contraceptives, being unmarried or having low educational level 5-10. Also younger age, low socioeconomic status, smoking cigarettes, a history of physical or sexual abuse and alcohol/drug abuse have been associated with repeat pregnancy termination 5-10. In contrast, a study in Denmark in 2007 showed no differences between women having first or subsequent pregnancy terminations 16. The lack of significant differences in that study may have been due to lack of statistical power to detect relatively small differences. In our study none of the identified risk factors more than doubled the odds ratio for having a repeat pregnancy termination.

    A longer period of exposure to sexual intercourse and thereby risk for pregnancy may explain the increased risk for repeat terminations in women above 25 years old in our study. Being single increased the risk for repeat pregnancy termination as well, in particular in women 25 years or older. Women with college or university education had lower risks for repeat pregnancy termination than women with primary school education only. These findings suggest that repeat pregnancy termination is related to socioeconomic factors, and that an unplanned pregnancy is more likely to be continued in women with a partner or with higher education. An alternative explanation is that women with a low educational level or women who are single, more often become pregnant unintentionally.

    Conclusion

    In this study of all requests for pregnancy termination in Norway during 2007–2011 a total of 36.7% were among women with a prior pregnancy termination. Age of 25 years or older, previous childbirth and use of contraception at the time of conception increased the risk of repeat pregnancy termination. Our findings therefore suggest that high fecundity may be an underlying risk factor. To prevent repeat pregnancy terminations, and thereby a large proportion of all terminations, women with a first time pregnancy termination may be an important target group.