Perinatal outcomes after induced termination of pregnancy by methods: A nationwide register-based study of first births in Finland 1996–2013
Perinatal outcomes after induced termination of pregnancy by methods: A nationwide register-based study of first births in Finland 1996±2013
Situ KC 0 1
Elina Hemminki 0
Mika Gissler 0
Suvi M. Virtanen 0 1
Reija Klemetti 0
0 Editor: Cornelis B Lambalk , VU medisch centrum , NETHERLANDS
1 School of Social Sciences, University of Tampere , Tampere , Finland , 2 Department of Health and Social Care Systems, National Institute for Health and Welfare , Helsinki , Finland , 3 Department of Information Services, National Institute for Health and Welfare , Helsinki , Finland , 4 Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden, 5 Department of Public Health Solutions, National Institute for Health and Welfare , Helsinki , Finland , 6 Department of Welfare, National Institute for Health and Welfare , Helsinki , Finland
This is a nationwide register-based study including 419,879 first-time Finnish mothers with
singleton birth during the time period 1996±2013. Mothers having their first birth were
identified from the Medical Birth Register and linked to the Abortion Register by their identification
numbers. Multinomial logistic regression analysis was performed to examine the risk for
preterm birth, low birth weight, small for gestational age and perinatal death by the method in
Among the first-time mothers, 87.0% had no history of TOPs, 3.2% had a history of medical
TOP(s), 9.2% had a history of surgical TOP(s) and 0.6% had a history of both (medical and
surgical) TOP(s). No significant differences in perinatal outcomes were found among the
women with surgical TOPs, compared to the women with no TOPs. In unadjusted analysis,
increased odds for preterm birth and low birth weight were found when comparing women
having previous surgical TOPs with medical TOPs. Even after the adjustment of potential
Data Availability Statement: Data are available
from the National Institute for Health and Welfare
and permission to use them was received from the
THL ethical committee. Confidentiality was
maintained while doing analysis. Permission to get
similar data can be applied from THL National
Institute for Health and Welfare, more information:
service telephone for research authorisation
applications tel. +358 29 524 6677. Permission to
get similar data can be applied from THL National
Institute for Health and Welfare, more information:
URL for research authorisation applications,
Women with previous terminations of pregnancy (TOPs) before their first birth have been
associated with poorer perinatal outcomes. However, previous studies on the perinatal
outcomes by the method in previous TOPs are inconsistent.
To examine the perinatal outcomes of the first-time mothers with singleton births, by the
method of previous TOP (medical and surgical vs no TOP, and surgical vs medical).
information-for-researchers and email address of
Funding: This work was supported by The Finnish
Cultural Foundation, Central Fund, Grant number:
00160409, received by SK. National Institute for
Health and Welfare is the funder that supported us
Competing interests: The authors have no
confounders, odds for preterm birth < 37 weeks (OR = 1.19, 95% CI = 1.04±1.36) and low
birth weight < 2500 g (OR = 1.16, 95% CI = 1.00±1.35) remained significant. After restricting
data to the single TOP, the results were similar; OR for both preterm birth and low birth
weight was 1.18 (95% CIs = 1.02±1.36 and 1.01±1.38).
Perinatal outcomes did not differ among the mothers with surgical TOPs compared to the
mothers with no TOPs, while the outcomes were poorer after surgical TOP(s) than after
In Europe, termination of pregnancies (subsequently TOPs) are common, and in Western
European countries most TOPs are performed before the first birth [
]. Finland has low rate of
TOP, and in 2014 the rate was 8.5 per 1,000 women aged 15±49 years old. The highest rate was
among women aged 20±24 years old (16.8 per 1,000 women), which is well below the mean
age (28.6 years old) of a woman's first childbirth [
A termination of pregnancy can be performed by surgical (dilatation and uterine
evacuation) or medical (antiprogestin mifepristone and misoprostol) methods. In Europe, medical
TOPs began in France in 1998 [
]. Mifepristone received authorization in Finland in 2000.
Since then, there have been increased use of medical termination of pregnancy and it was
nearly 90% in 2014 [
Whether or not an induced termination of pregnancy prior to the first birth adversely
influences the outcome of that birth has been previously debated [4±8]. There are evidences of an
increased risk of preterm birth with many TOPs prior to the first birth [5±8], but these results
refer to the time period when most TOPs were surgical. However, some studies did not found
an association between previous TOPs and preterm birth/ low birth weight [4,9±11].
Few studies have considered the method of TOPs, with regard to the outcomes in
subsequent birth [9,12±18]. Some studies have reported a higher risk of preterm birth and low birth
weight after surgical TOPs, when compared to medical TOPs [
], but others have found
no increased risk in outcomes between these methods [
]. Although no other studies
have taken into account the number of TOPs when comparing these methods, a study from
] has reported an increased risk for preterm birth among those mothers with
repeated surgical TOPs, compared to those mothers with repeated medical TOPs.
A previous study from Finland found an increased risk for poorer perinatal outcomes after
many TOPs, however data was too scant to study the outcomes by the method of abortion [
Thus the purpose of this study was to examine the perinatal outcomes of first-time mothers
with singleton birth by the method of TOP: medical and surgical vs no TOP, and surgical vs.
medical TOP(s), while adjusting for confounding factors. Additionally, comparisons were
made between those mothers with only one previous TOP in their reproductive histories.
The study was approved by the ethical committee of National Institute for Health and Welfare
(THL). A positive statement from THL ethics committee (22.10.2009), a positive statement
with regard to the amendment of the data, and a permission to use the data were received
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from THL (25.10.2014). The information used in this study were anonymized prior the
In this population-based cohort study, we used the nationwide Medical Birth Register
(MBR) and Abortion Register (AR), which were maintained by the National Institute for
Health and Welfare (THL). All the mothers having had their first birth during the time period
ranging from 1996 to 2013 were identified from the MBR, and these mothers were linked to
the AR to determine the TOPs (1983±2013) they had prior to their first birth. The MBR was
started in 1987, and it contains information about each mother's background characteristics,
care during pregnancy and delivery, and newborn care up to 7 days of age [
]. The AR has
been functional since 1950, and computerized data are available since 1983 [
]. The register
contains information on a woman's background, gestational age, indication for TOPs, dates,
procedures and complications occurring during the process [
]. Overall, the information in
both registers is relatively complete, and the data quality is high [19±20].
For this study, the mothers were divided into four study groups by their TOP histories and
methods: no prior TOP, medical TOPs only, surgical TOPs only and both types of TOPs. The
medical TOPs included TOPs performed using mifepristone alone, or in combination with
misoprostol. Surgical TOPs included TOPs performed using either dilatation and curettage or
vacuum aspiration. Mothers who had undergone multiple TOPs using both medical and
surgical methods were included in both types of TOPs. Only the mothers with successful TOPs
were included. The proportion of failed TOPs is very low; 0.4% in 2009±2015 according to the
The outcome measures, gestational age at birth, birth weight, small for gestational age and
perinatal death were retrieved from the MBR. The gestational age at birth in the MBR is the
clinicians' best estimate at birth, based on ultrasound examination(s) and the date of last
menstruation. The birth was defined as preterm if the gestational age at birth was less than 37
weeks, very preterm if the gestational age at birth was less than 32 weeks and extremely
preterm if the gestational age was less than 28 weeks. Birth weights of less than 2,500 grams and
1,500 grams were defined as low birth weight and very low birth weight, respectively. Small for
gestational age (SGA) was defined according to sex-specific Finnish standards for newborn
infants between 24 and 43 gestation weeks [
]. Perinatal deaths referred to stillbirths from 22
weeks of gestation and early neonatal deaths until the end of the first week after birth.
The background characteristics of women were received from the MBR and they refer to
the time of the birth of the baby. The urbanity of the maternal municipality of residence was
categorized according to Statistics Finland, and the categories were further grouped into
urban, semi-urban, rural and abroad. In the MBR, marital status of mothers was categorized
into seven categories; married and living together with spouse, registered partnership, married
and living separated from spouse, never married, divorced, widowed and unknown. These
were further categorized into three groups; married/cohabiting, unmarried/single and
unknown. In this study, we treated all variables as categorical variables. Information
concerning socioeconomic status of the mothers was incomplete. So, maternal smoking and urbanity
of municipality were used to explain the socioeconomic status of mothers.
The statistical software, SPSS 23, was used for the analysis. Cross tabulations based on the
study groups were calculated and chi-square test were used to study statistical significance.
The level of statistical significance was set at p<0.05. Those mothers with previous surgical
TOPs and those with previous medical TOPs were separately compared to women with no
previous TOP, adjusting for differences in their background characteristics using a
multivariate logistic regression (odds ratio and 95% confidence interval). The potential confounders
were selected on the basis of the previous literature on the maternal risk factors of birth
outcomes, and their availability and quality in the registers. Mothers with previous TOPs (surgical
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or medical) were compared to those without previous TOP, after adjusting for the maternal
age, marital status, urbanity of the municipality of residence, history of smoking during
pregnancy and the year of childbirth.
Mothers with previous surgical TOPs were compared to those with previous medical
TOPs, after adjusting for the maternal age, marital status, urbanity of the municipality of
residence, history of smoking during pregnancy and the year of childbirth. In the second
model, additional adjustments (number of previous TOPs, gestational age at TOP and
year of last TOP) were added. Since the number of women having had both medical and
surgical TOPs was small when compared to the other groups, these mothers were excluded
from the regression analysis. Lastly, a sub-analysis for those mothers having had only one
previous surgical or medical TOP was conducted, after adjusting for the same confounders
A total of 419,879 first-time mothers having had singleton birth from 1996±2013 were
identified from the MBR. According to the AR, 365,356 (87.0%) of the mothers had no history of
TOP, 13,450 (3.2%) had histories of medical TOP(s), 38,659 (9.2%) had histories of surgical
TOP(s) and 2,414 (0.6%) had histories of both medical and surgical TOP(s). The background
characteristics differed with regard to several aspects between these subgroups (Table 1). The
mothers with histories of previous TOPs were more often younger, single, urban residents and
smokers than the mothers without previous TOP. When compared to the mothers with
previous medical TOPs, the mothers with previous surgical TOPs had more repeated TOPs, had
their last TOP in earlier years, and the time difference between their first birth and last TOP
was longer (Table 2).
When compared to those mothers with no previous TOP, the perinatal outcomes were
poorer among those mothers with previous surgical or both types of TOPs, but not among the
mothers with previous medical TOPs only (Table 3). The incidence of preterm birth was lower
among the mothers with previous medical TOPs, when compared to those mothers without
The unadjusted logistic regression analysis showed increased risk for all types of preterm
birth and low birth weight after surgical TOPs and decreased risk for all studied perinatal
outcomes after medical TOPs, when compared to the mothers without previous TOP (Table 4).
Compared to the mothers with previous medical TOPs, the mothers with previous surgical
TOPs had increased risk for all studied outcomes, with the exception of SGA and perinatal
After adjusting for the sociodemographic factors, the mothers with previous medical TOPs
had decreased risk for preterm birth and low birth weight when compared to the mothers with
no previous TOPs (Table 4). The increased risk for adverse outcomes when comparing the
mothers with surgical TOPs to the mothers with no TOPs, did not remain significant, after
controlling for background characteristics. However, mothers with surgical TOPs had
marginally increased risk for SGA compared to the mothers with no TOPs.
The mothers with previous surgical TOPs had higher risk for preterm birth and newborn
with low birth weight than those mothers with previous medical TOPs (Table 4). After an
additional adjustment for the number of previous TOPs, the gestational age at the time of
TOP, year of the last TOP, risk for preterm birth (<37 weeks) and risk for newborn with low
birth weight remained significant (Table 4).
After restricting the analysis to those mothers having had only one previous TOP, and
adjusting for confounders, the results did not change: the mothers having had only one
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previous surgical TOP had increased risks for preterm birth and low birth weight when
compared to the mothers with only one previous medical TOP (Table 4).
The first-time mothers with previous TOP were much younger, single and more often smokers
than the mothers without previous TOP. In addition, the mothers with previous medical TOPs
had a reduced risk for preterm birth and low birth weight when compared with the mothers
with no previous TOP. All the poor outcomes measured, with the exception of small for
gestational age and perinatal deaths, were more common among the mothers with previous surgical
TOPs than among the mothers with previous medical TOPs. This was also true among those
mothers who had gone through only one TOP before their first birth.
Our nationwide study covered all the first-time mothers having had singleton births during
the time period ranging from 1996 to 2013, and all of the TOPs performed in Finland during
the time period ranging from 1983 to 2013. Because our data did not include TOPs before
1983, some women might have been classified wrongly into the ªno TOP groupº. However, we
assume that there are only few such cases and this will thus not affect our results. The quality
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of the data from the THL and AR is considered to be very high and reliable [
], and earlier
studies have compared the information in the medical records with the AR and found that
95% of the information matched and 99% data coverage [
]. Our large data set enabled us
to study the outcomes in different subgroups, based on the method of terminating pregnancy.
Even though we were able to study the outcomes by the method we were not able to separate
different medical (mifepristone/misoprostol) or surgical methods (dilatation, curettage or
vacuum aspiration) because the register do not contain as detailed information. Furthermore, this
is an observational study and it cannot provide evidences for causality.
Overall, our findings that the demographic and reproductive profiles of first-time mothers
with histories of previous TOPs differed from those of first-time mothers without histories of
previous TOPs are in line with previous studies [
]. In the multivariate logistic
regression analysis, we were able to adjust for several background variables; however, we could not
adjust for the socioeconomic position of the mothers due to incomplete data (data not shown).
No prior TOP
(n = 365356)
(n = 13450)
Adjusted Model I- adjusted for socio demographic factors; maternal age, marital status of mothers, area of residence, smoking status and year of child birth
Adjusted Model II- adjusted for number of previous TOPs, gestational age at TOP and the year of last TOP
1 No TOP group is used as reference group
2 Medical group is used as reference group
3 Medical group is used as reference group and includes mothers with only one medical and one surgical TOP
In Finland, smoking has been found to be a good proxy for the socioeconomic position [
therefore, we used urbanity of municipality and mother's smoking instead.
Previously, it has been reported that undergoing several TOPs before a woman's first birth
correlated with poorer perinatal outcomes in subsequent births [5±8]. However, we compared
the mothers with histories of surgical and medical TOPs, but adjusted for the number of
previous TOPs. Moreover, we conducted a subgroup analysis of those having had only one surgical
or medical TOP. We also adjusted for the gestational age at the time of TOP and the year of
the last TOP, which has not been done in previous studies [
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There are few studies examining the long-term consequences of medical TOPs [
However, our finding of a reduced risk of preterm births among the mothers with previous
medical TOPs, when compared to the mothers with no previous TOP, is consistent with a
previous study from China [
]. In addition, some other studies [
] indirectly support our
finding of no increased risk for preterm births among the mothers with history of medical
TOPs. Having had a TOP reflects fertility, and this may explain the better outcomes among
those mothers having had medical TOPs compared to the mothers without history of TOPs.
Poorer outcomes after surgical TOPs might be due to the reason that the medical TOPs cause
less physical trauma to the cervix and the less endometrial damage than the surgical TOPs
As in some prior studies, our unadjusted results showed an increased risk for preterm births
among those mothers with surgical TOPs, when compared with those mothers having had no
prior TOPs [
]. However, in our study, the significance was lost after adjusting for
the sociodemographic factors.
Similar to some previous studies [
], we found a higher risk for preterm births
among the mothers with previous surgical TOPs, when compared to the mothers with
previous medical TOPs. Medical TOPs may cause less harm to the uterus than surgical TOPs,
which can result in better birth outcomes later [
]. A recent review and meta-analysis
from 21 studies also supports our findings with regard to the association between preterm
births and surgical TOPs [
]. In contrast, some previous studies have not found an increased
risk for preterm births in subsequent births among mothers with previous surgical TOPs,
when compared to mothers with previous medical TOPs [
]. However, some of those
studies did not control for potential confounders, and some were based on self-reported
TOPs, which may introduce recall bias [
Contrary to some of the previous research, our study reported an increased risk for
lowbirth weight among the mothers with previous surgical TOPs, when compared to the mothers
with previous medical TOPs [12±14,16]. However, few studies found a positive association
between surgical TOPs and the risk of low birth weight [
], which might support our findings.
Perinatal outcomes did not differ among the mothers with surgical TOPs compared to the
mothers with no TOPs, while the outcomes were poorer after surgical TOP(s) than after
medical TOP(s). It is important to study the effects of the different methods used for terminating
pregnancy to determine the safest method. This could be of importance for healthcare
professionals in terms of clinical decision making and counselling women seeking termination of
pregnancy, with respect to the method used for termination.
Conceptualization: Situ KC, Elina Hemminki, Mika Gissler, Reija Klemetti.
Data curation: Mika Gissler.
Formal analysis: Situ KC.
Funding acquisition: Situ KC, Reija Klemetti.
Investigation: Situ KC, Reija Klemetti.
Methodology: Situ KC, Reija Klemetti.
Project administration: Situ KC, Mika Gissler, Reija Klemetti.
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Resources: Situ KC, Suvi M. Virtanen, Reija Klemetti.
Software: Situ KC.
Validation: Situ KC.
Supervision: Suvi M. Virtanen, Reija Klemetti.
Visualization: Situ KC, Elina Hemminki, Mika Gissler, Reija Klemetti.
Writing ± original draft: Situ KC.
Writing ± review & editing: Situ KC, Elina Hemminki, Mika Gissler, Suvi M. Virtanen, Reija
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