Induced abortions of women living with HIV in Finland 1987–2019: a national register study

Before effective methods to prevent vertical transmission were discovered studies reported an increased proportion of pregnancies ending in induced abortion after HIV diagnosis [1, 2]. Development of antiretroviral treatment (ART) has reduced the risk of vertical transmission in European cohort studies from 15 to 20% in the pre-ART era to 10% with mono-ART and to less than 1% in the current era of combined ART (cART) [3‐7]. Although over 80% of the nearly 50,000 women newly diagnosed with HIV in Europe in 2018 were fertile-aged [8], little is known about the rates and risk factors for induced abortions among women living with HIV (WLWH). Most data come from limited questionnaire studies with varying response rates [9‐11]. In questionnaire studies on the general population, induced abortions have been significantly underreported [12‐14]. The risk factors for WLWH having an induced abortion have included younger age, earlier year of HIV diagnosis, and transmission by intravenous drug use (IDU) [15].

In Finland, an indication is needed for induced abortion but 95% of abortions are performed on social indications [16]. Induced abortion is widely available and inexpensive in public health care. Since HIV testing at an induced abortion is currently not routinely recommended, the prevalence of undiagnosed HIV at the time of induced abortion is unknown.

The aim of the study was to use Finnish national health register data to 1) determine the nationwide rate of induced abortions of WLWH in Finland in 1987–2019, 2) compare the rates of induced abortions before and after HIV diagnosis over different time periods, 3) determine the factors associated with terminating a pregnancy after HIV diagnosis, and 4) estimate the prevalence of undiagnosed HIV at induced abortions to see whether routine testing should be implemented.

This is a nationwide retrospective study combining data from several national registers. The study population consisted of all women who were diagnosed with or treated for HIV in Finland before 1 January 2020, were fertile-aged (15–49 years) between 1987 and 2019, and had a valid personal identification code (PIC; granted to all citizens and immigrants with a permit to stay at least 1 year). The women were identified from the Finnish HIV Quality of Care Register (FINHIV), which is described in detail elsewhere and consists of all people diagnosed with or treated for HIV in Finland since 1 January 1984 [17]. Sex in the register is reported predominantly based on the PIC which is sex-specific (categories female/male); generally this means sex assigned at birth.

Using the PIC as an identification, data from the FINHIV were combined with two national registers maintained in the Finnish Institute for Health and Welfare (THL): Register on Induced Abortions and Sterilizations, and Medical Birth Register. Reporting induced abortions, sterilizations, and births to their respective registers is mandatory by law, and the electronical information is available since 1983 (induced abortions), 1987 (sterilizations), and 1987 (births). The following variables were collected: from the FINHIV date of birth, date of death, date of HIV diagnosis, transmission route, country of birth, date of immigration, date of emigration, first CD4+ cell count and its date, date of AIDS diagnosis, hepatitis C antibodies (positive/negative), hepatitis B S-antigen (positive/negative), and date of latest contact to HIV care (e.g. date of latest HIV viral load); from the Register on Induced Abortions and Sterilizations date of abortion, gestational age at abortion, indication for abortion, and date of sterilization; from the Medical Birth Register date of delivery and gestational age at birth. Because only data on induced abortions in Finland were available and the immigration and emigration data in the FINHIV are incomplete, the estimated follow-up time was corrected for those not born in Finland with dates of first and latest recorded contact to health care. These were collected from the Care Register for Health Care and Register for Primary Health Care Visits (maintained at THL; earliest data from 1994 and 2011, respectively).

For women born in Finland, the start of the follow-up was defined as 1 January 1987 or the day they turned 15 years of age, whichever later. The end of the follow-up was defined as 31 December 2019, the date of turning 50 years of age or, when applicable, date of death, sterilization or emigration. For women not born in Finland, we used additional cut-off points to correct for the time before immigration and the increased rate of emigration: for the start of follow-up, they consisted of the date of immigration as recorded in the FINHIV or the first recorded health care contact (including the date of first delivery or induced abortion). Similarly, for the end of the follow-up the additional cut-off point was the last recorded date of health care contact. Formation of the study population is depicted in Fig. 1.

The date of HIV diagnosis is most often recorded as the date the first positive HIV antigen/antibody test was taken, and there is a delay of approximately 7 days before a positive result is confirmed. Arranging an induced abortion takes a minimum of 3 days. Therefore, an induced abortion was considered to have taken place before the HIV diagnosis (i.e., positive HIV test result could not have affected the decision to have an induced abortion) if the date of the abortion was before the date of HIV diagnosis, or the HIV diagnosis date was no more than 10 days prior to the date of abortion. If the HIV diagnosis date was earlier than 10 days prior to the date of abortion, the abortion was considered to have taken place after the HIV diagnosis.

To estimate the maximum prevalence of undiagnosed HIV at the time of induced abortion, we examined all induced abortions taking place 0–5 years before HIV diagnosis during 1987–2014. Additionally, we used the CD4-positive lymphocyte count at HIV diagnosis (if measured 0–90 days after HIV diagnosis) to assess whether the women had been infected at the time of the last induced abortion. The thresholds for approximating the time passed since transmission were based on calculations by Lodi et al. [18] where the median times for 25–30-year-old heterosexual women from seroconversion to CD4+ cell count dropping below 500 cells/μL, 350 cells/μL, and 200 cells/μL were 1.63, 5.66, and 10.71 years, respectively. We set the thresholds for probable minimum time as infected at 6 months for those with CD4+ cell count over 500 cells/μL, 1 year for those with CD4+ cell count 350–499 cells/μL, 3 years for those with 200–349 cells/μL, and 5 years for those under 200 cells/μL. The calculated maximum and minimum numbers of induced abortions with undiagnosed HIV were then compared to the total number of induced abortions in the time period as recorded in the Register of Induced Abortions and Sterilizations [19]. We also evaluated the prevalence for some subgroups: women not born in Finland, women with previous induced abortions, and women with previous deliveries. The total of induced abortions performed for these subgroups was estimated from THL open data [19] for previous pregnancies and from articles by Malin et al. [20] and Heino et al. [16] for women not born in Finland.

For statistical analysis, SPSS 27.0 (IBM, Chicago, Illinois, USA) and Stata 17 (StataCorp LLC, College Station, Texas, USA) were used.

The study consists of 1017 women described in Table 1. The total follow-up time was 15,807 years (median 14.5 years, IQR 8.4–22.1), with 6509 years before and 9297 years after HIV diagnosis. A total of 249 women (24.5% of the study population) had 396 induced abortions. The number of abortions per woman ranged from 1 to 6, with 154 (61.8%) having one abortion, 61 (24.5%) having two, and 34 (13.0%) having three or more. The indication for induced abortion was recorded in 386 cases (97.5%); social circumstances for 349 (90.4% of those recorded), under 17 years of age in 13 (3.4%), endangerment of the woman’s health in 11 (2.8%), fetal indication in 6 (1.6%), and other indication in 7 (1.8%).

The induced abortion rate during 1987–2019 was 25.1 abortions/1000 follow-up years. It decreased from 42.8 abortions/1000 follow-up years during 1987–1997 to 14.7 abortions/1000 follow-up years during 2009–2019, with the decrease more prominent in induced abortions after diagnosis (Fig. 2).

To better assess the effect of the HIV diagnosis on the rate of induced abortion, we also examined separately the 5 years before and after HIV diagnosis for those who had follow-up time both before and after the diagnosis (i.e., diagnosed in Finland aged 15–49 years; n = 689). For those diagnosed in 1987–1997, the rate of abortions was higher after the HIV diagnosis (51.2 compared to 35.4 abortions/1000 follow-up years) while for those diagnosed in 1998–2008 the rate was lower after diagnosis (24.9 compared to 45.0 abortions/1000 follow-up years), and for those diagnosed in 2009–2019, there was little change before and after diagnosis (Fig. 3).

In the multivariable logistic regression model HIV diagnosis during or before pregnancy was associated with a decreased risk of induced abortion in 1998–2008 and 2009–2019 compared to 1987–1997 (Table 2). Increasing age was associated with a decreasing risk. In the model an increasing number of previous abortions or deliveries were both associated with an increased risk of induced abortion in women who were not born in Finland. Transmission route, hepatitis B and hepatitis C were not significant factors in any of the constructed models and are not included in the final models.

In analyzing factors associated with the risk of terminating a pregnancy specifically in pregnancies that began after HIV diagnosis in 1998–2019, the results were similar (Table 3). Not being born in Finland and previous induced abortions and pregnancies were associated with an increased risk of terminating a pregnancy, while increasing age was associated with a decreasing risk.

There were 68 women who had 88 induced abortions during 1987–2014 within 5 years before HIV diagnosis. During the same years, 304,985 induced abortions were performed in Finland, which makes the maximum prevalence of undiagnosed HIV 0.29/1000 abortions for those years. By using the CD4+ cell count thresholds, we estimated that of the 40 abortions where the woman had a CD4+ cell count at diagnosis available, HIV was undiagnosed at 11 abortions (28%). Assuming this percentage would hold true for the 88 abortions, the minimum prevalence of undiagnosed HIV would be 0.08/1000 induced abortions for 1987–2014 (Table 4).

The estimated maximum prevalence for women not born in Finland, women with previous induced abortions, and women with previous deliveries were 1.19, 0.41 and 0.23/1000 induced abortions, respectively. Of those women not born in Finland who had an induced abortion 0–5 years before HIV diagnosis, all but one were born in countries where the prevalence of HIV is considered high enough (> 1%) to warrant opt-out screening of HIV for refugees, asylum seekers and immigrants after arrival in Finland [21, 22].

Because both the time frame for development of symptomatic HIV infection prompting testing and the rate of decline for CD4+ cells are varied and uncertain, we did a sensitivity analysis by changing the time frame and thresholds to 10 and 15 years before HIV diagnosis and the results did not change significantly.

The rate of induced abortions among WLWH in Finland has decreased markedly in three decades, approaching the rate among the general population. In our model, being diagnosed with HIV was not associated with an increased risk of terminating a pregnancy after effective cART to prevent vertical transmission became available. However, since every woman living with HIV in Finland meets her doctor once or twice a year with the possibility to discuss family plans and contraception, one might assume the rate of induced abortions among WLWH to be even lower. Caregivers in Finland should remember to discuss the wishes of WLWH regarding family planning at every follow-up appointment, and especially with younger women, women with previous pregnancies, and women who were not born in Finland.

Routine testing of all women at induced abortion is not likely to be cost-effective in Finland due to low HIV prevalence, but testing could be offered to women with pre-existing risk factors, such as being born in a country with a high HIV prevalence.