Prior uterine evacuation of pregnancy as independent risk factor for preterm birth: a systematic review and metaanalysis




Background


Preterm birth (PTB) is the number one cause of perinatal mortality. Prior surgery on the cervix is associated with an increased risk of PTB. History of uterine evacuation, by either induced termination of pregnancy (I-TOP) or spontaneous abortion (SAB), which involve mechanical and/or osmotic dilatation of the cervix, has been associated with an increased risk of PTB in some studies but not in others.


Objective


The objective of the study was to evaluate the risk of PTB among women with a history of uterine evacuation for I-TOP or SAB.


Data Sources


Electronic databases (MEDLINE, Scopus, ClinicalTrials.gov , EMBASE, and Sciencedirect) were searched from their inception until January 2015 with no limit for language.


Study Eligibility Criteria


We included all studies of women with prior uterine evacuation for either I-TOP or SAB, compared with a control group without a history of uterine evacuation, which reported data about the subsequent pregnancy.


Study Appraisal and Synthesis Methods


The primary outcome was the incidence of PTB < 37 weeks. Secondary outcomes were incidence of low birthweight (LBW) and small for gestational age (SGA). We planned to assess the primary and the secondary outcomes in the overall population as well as in studies on I-TOP and SAB separately. The pooled results were reported as odds ratio (OR) with 95% confidence interval (CI).


Results


We included 36 studies in this metaanalysis (1,047,683 women). Thirty-one studies reported data about prior uterine evacuation for I-TOP, whereas 5 studies reported data for SAB. In the overall population, women with a history of uterine evacuation for either I-TOP or SAB had a significantly higher risk of PTB (5.7% vs 5.0%; OR, 1.44, 95% CI, 1.09–1.90), LBW (7.3% vs 5.9%; OR, 1.41, 95% CI, 1.22–1.62), and SGA (10.2% vs 9.0%; OR, 1.19, 95% CI, 1.01–1.42) compared with controls. Of the 31 studies on I-TOP, 28 included 913,297 women with a history of surgical I-TOP, whereas 3 included 10,253 women with a prior medical I-TOP. Women with a prior surgical I-TOP had a significantly higher risk of PTB (5.4% vs 4.4%; OR, 1.52, 95% CI, 1.08–2.16), LBW (7.3% vs 5.9%; OR, 1.41, 95% CI, 1.22–1.62), and SGA (10.2% vs 9.0%; OR, 1.19, 95% CI, 1.01–1.42) compared with controls. Women with a prior medical I-TOP had a similar risk of PTB compared with those who did not have a history of I-TOP (28.2% vs 29.5%; OR, 1.50, 95% CI, 1.00–2.25). Five studies, including 124,133 women, reported data about a subsequent pregnancy in women with a prior SAB. In all of the included studies, the SAB was surgically managed. Women with a prior surgical SAB had a higher risk of PTB compared with those who did not have a history of SAB (9.4% vs 8.6%; OR, 1.19, 95% CI, 1.03–1.37).


Conclusion


Prior surgical uterine evacuation for either I-TOP or SAB is an independent risk factor for PTB. These data warrant caution in the use of surgical uterine evacuation and should encourage safer surgical techniques as well as medical methods.


Preterm birth (PTB) is the number one cause of perinatal mortality in many countries, including the United States. Defining risk factors for prediction of PTB is an important goal for several reasons. First, identifying women at risk allows initiation of risk-specific treatment. Second, it may define a population useful for studying particular interventions. Finally, it may provide important insights into the mechanisms leading to PTB.


Prior surgery on the cervix, such as cone biopsy and loop electrosurgical excision procedure, is associated with an increased risk of spontaneous PTB. A history of uterine evacuation, by either induced termination of pregnancy (I-TOP) or treatment of spontaneous abortion (SAB) by suction dilation and curettage or by dilation and evacuation (D&E), which may involve mechanical and/or osmotic dilatation of the cervix, has been associated with an increased risk of PTB in some studies but not in others.


Some studies have also postulated that the method of uterine evacuation may influence the association (or not) with PTB. Moreover, with recent increases in the use of medications (misoprostol and mifepristone), it would be important to assess outcomes in subsequent pregnancies after medical termination of pregnancy as the element of cervical trauma is minimized with these techniques.


The aim of this metaanalysis was to evaluate the risk of PTB among women with a history of uterine evacuation for either I-TOP or SAB.


Materials and Methods


Search strategy


Electronic databases (ie, MEDLINE, Scopus, ClinicalTrials.gov , EMBASE, Sciencedirect) were searched from their inception until January 2015 with no limit for language. Search terms used were the following key words: low birthweight, premature birth, preterm birth, small for gestational age, miscarriage, pregnancy, premature, newborn, uterine evacuation, abortion, induced abortion, spontaneous abortion, termination of pregnancy, curettage, first trimester, second trimester, mifepristone, misoprostol, laminaria, subsequent, and dilatation and evacuation; dilation and curettage; spontaneous preterm birth.


In addition, the reference lists of all identified articles were examined to identify studies not captured by electronic searches. The electronic search and the eligibility of the studies were independently assessed by the authors (G.S. and V.B.). Differences were resolved by discussion.


Study selection


We included all studies of women with prior uterine evacuation for either I-TOP or SAB, compared with a control group without prior uterine evacuation, which reported data about the subsequent pregnancy. We excluded studies without a control group (eg, case series) as well as studies about stillbirth.


I-TOP was defined as an intervention to voluntarily terminate a pregnancy (ie, induced abortion) by either surgical or medical means so it does not result in a live birth. SAB was defined as spontaneous intrauterine pregnancy loss prior to 20 weeks. Surgical uterine evacuation (for either I-TOP or SAB) was defined as a procedure using surgical instruments, either D&E or vacuum aspiration (VA), to remove the fetus and placenta from the uterus.


D&E was defined as a procedure that includes mechanical cervical dilatation (usually by using uterine dilators of increasing diameter to stretch the cervix) followed by the removal of uterine contents using a combination of suction and instruments (eg, sharp curette, ring clamp, or forceps). VA was defined as evacuation of the uterine contents using an electric vacuum aspirator or manual vacuum aspirator. Medical uterine evacuation (for either I-TOP or SAB) was defined as a nonsurgical uterine evacuation in which pharmaceutical drugs are used to empty the uterus. Therefore, we had the potential for several sensitivity analyses according to the type of abortion ( Table 1 ).



Table 1

Potential overall, sensitivity, and subgroup analyses planned
























































































Intervention group Control group
Overall analysis
Prior uterine evacuation (I-TOP and SAB) No prior uterine evacuation
Planned sensitivity analyses in women with prior uterine evacuation for I-TOP
Prior I-TOP No prior I-TOP
Prior surgical (either D&E or VA) I-TOP No prior I-TOP
Prior surgical I-TOP by D&E No prior I-TOP
Prior surgical I-TOP by VA No prior I-TOP
Prior surgical I-TOP by D&E Prior surgical I-TOP by VA a
Prior medical I-TOP No prior I-TOP
Planned sensitivity analyses in women with prior uterine evacuation for SAB
Prior SAB No prior SAB
Prior surgical (either D&E or VA) SAB No prior SAB
Prior surgical SAB by VA No prior SAB
Prior surgical SAB by D&E No prior SAB
Prior surgical SAB by D&E Prior surgical SAB by VA a
Prior medical SAB No prior SAB
Planned sensitivity analyses comparing I-TOP with SAB
Prior uterine evacuation for I-TOP Prior uterine evacuation for SAB a
Planned subgroup analyses in study on I-TOP and in study on SAB, separately
Only 1 prior uterine evacuation No prior uterine evacuation
More than 1 prior uterine evacuation No prior uterine evacuation
More than 1 prior uterine evacuation Only 1 prior uterine evacuation a
Prior uterine evacuation in singletons No prior uterine evacuation in singletons
Prior uterine evacuation in multiple gestations No prior uterine evacuation in multiple gestations
Prior uterine evacuation in cohort studies No prior uterine evacuation in cohort studies
Prior uterine evacuation in case-control studies No prior uterine evacuation in case-control studies
According to gestational age at uterine evacuation

D&E , dilation and evacuation; I-TOP , induced termination of pregnancy; SAB , spontaneous abortion; VA , vacuum aspiration.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016.

a Because none of the included studies evaluated this outcome, we used an indirect comparison metaanalysis to assess this outcome.



Primary and secondary outcomes were planned a priori. The primary outcome was the incidence of PTB (ie, preterm delivery < 37 weeks). Secondary outcomes were neonatal outcomes including incidence of low birthweight (birthweight < 2500 g) and of small for gestational age (birthweight < 10th percentile for gestational age).


We planned to assess the primary and the secondary outcomes in the overall population as well as in studies on I-TOP and SAB, separately. We also planned several subgroup analyses according to the number of prior uterine evacuation; the number of fetuses in the index pregnancy; the gestational age at abortion; or the type of the study (either cohort or case-control study) ( Table 1 ). We assessed these subgroup analyses for only the primary outcome (ie, incidence of PTB) in both surgical and medical I-TOP and SAB, separately and not in the overall combined data ( Table 1 ).


Data extraction and risk of bias assessment


Data abstraction was completed by 2 independent investigators (G.S. and V.B.). Each investigator independently abstracted data from each study separately. Data from each eligible study were extracted without modification of original data onto custom-made data collection forms. Differences were resolved by consensus. Information of confounders adjusted and adjusted risk estimates were collected when available. When possible, all authors were contacted for missing data.


Reviewers (G.S. and V.B.) independently assessed the risk of bias of the included studies via the Methodological Index for Non-Randomized Studies. Seven domains related to risk of bias were assessed in each study: (1) aim (ie, clearly stated aim), (2) rate (ie, inclusion of consecutive patients and response rate), (3) data (ie, prospective collection of data), (4) bias (ie, unbiased assessment of study endpoints), (5) time (ie, follow-up time appropriate), (6) loss (ie, loss to follow-up), and (7) size (ie, calculation of the study size). Review authors’ judgments were categorized as low risk, high risk, or unclear risk of bias. Discrepancies were resolved by discussion.


Data analysis


The data analysis was completed independently by two authors (G.S. and V.B.) using Review Manager 5.3 (Copenhagen, Denmark: The Nordic Cochrane Centre, Cochrane Collaboration, 2014). Discrepancies were resolved by discussion.


Heterogeneity across studies was assessed using the Higgins I 2 test. In case of statistically significant heterogeneity (I 2 > 0%), the random-effects model of DerSimonian and Laird was used; otherwise, in case of no inconsistency in risk estimates (ie, I 2 = 0%), a fixed-effect model was managed. The pooled results were reported as odds ratio (OR) with 95% confidence interval (CI).


For the outcomes not directly assessed by any of the included studies, an indirect comparison metaanalysis was performed ( Table 1 ). In the indirect comparison metaanalyses, data were combined in a 2-stage approach in which outcomes were analyzed in their original study and then summary statistics combined using standard summary data metaanalysis techniques to give an overall measure of effect (summary relative risk with 95% CI).


For studies that reported both unadjusted and adjusted risk for confounders statistically proven, we performed metaanalyses using a generic inverse variance method to obtain the adjusted risk estimate (aOR) of the primary outcome (ie, incidence of PTB). We assessed the aOR only for the primary outcome (ie, incidence of PTB) in studies on both surgical and medical I-TOP and SAB, separately.


Before data extraction, the review was registered with the PROSPERO International Prospective Register of Systematic Reviews (registration number CRD42015026482). Therefore, all the analyses and the outcomes were planned a priori before the data extraction.


The metaanalysis was reported following the Preferred Reporting Item for Systematic Reviews and Meta-Analyses statement.




Results


Study selection and study characteristics


We included 36 studies in this metaanalysis (1,047,683 women). The flow of study identification is shown in Figure 1 . Risk of publication bias was assessed by visual inspection of funnel plot; the symmetric plot suggested no publication bias ( Figure 2 ). Publication bias, assessed using Begg’s and Egger’s tests, showed no significant bias ( P = .87 and P = .71, respectively).




Figure 1


Flow diagram of studies identified in the systematic review

I-TOP , induced termination of pregnancy; PTB , preterm birth; SAB , spontaneous abortion.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016.



Figure 2


Funnel plot for assessing publication bias

OR , odds ratio.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016 .


Thirty-one studies reported data about prior uterine evacuation for I-TOP, whereas 5 studies reported data regarding prior uterine evacuation for SAB ( Tables 2 , 3 , and 4 ).



Table 2

Characteristics of the included studies on surgically induced termination of pregnancy









































































































































































































































































Study Study location Type of study Number of included women Method of abortion GA at abortion Confounders adjusted Primary outcome
Pantelakis et al, 1973 Greece Case-control 4779 Surgical N/A None PTB
Papaevangelou et al, 1973 Greece Retrospective cohort 3467 Surgical N/A None PTB
Daling and Emmanuel, 1975 Taiwan Retrospective cohort 1516 Surgical N/A None PTB
Daling and Emmanuel, 1977 United States Retrospective cohort 553 D&E N/A None PTB
Van der Slikke and Treffers, 1978 The Netherlands Case-control 3432 Surgical N/A None GA at delivery
World Health Organization, 1979 Europe Retrospective cohort 3352 Surgical N/A None GA at delivery
Obel, 1979 Denmark Prospective cohort 497 Surgical N/A None Placental complications
Mandelin and Karjalainen, 1979 Finland Prospective cohort 696 Surgical N/A None Birthweight
Meirik et al, 1982 Sweden Prospective cohort 1442 Vacuum < 13 wks Marital status, smoking Birthweight
Linn et al, 1983 United States Retrospective cohort 9823 Surgical N/A Age, ethnicity, smoking, economic status, parity Birthweight
Meirik et al, 1983 Sweden Retrospective cohort 1292 Vacuum < 13 wks Marital status, smoking PTB
Meirik et al, 1984 Sweden Prospective cohort 269 Prostaglandins followed by D&E < 13 wks Parity PTB
Park et al, 1984 Korea Case-control 681 Surgical None N/A PTB
Frank et al, 1985 United Kingdom Prospective cohort 1545 Surgical < 22 wks Age, marital status, gestational age at entry LBW
Pickering and Forbes, 1985 United Kingdom Population-based cohort study 7000 Surgical N/A Maternal age, height, sex of infant, marital status, social class PTB
Lekea-Karanika et al, 1990 Greece Case-control 4391 Surgical N/A Race, smoking PTB
Martius et al, 1998 Germany Population-based case-control study 106,124 Surgical N/A Gravidity, uterine surgery, type of work, urinary tract infection PTB
Zhou et al, 1999 Denmark Retrospective cohort 64,125 Surgical <14 wks Maternal age PTB
Henriet and Kaminski, 2001 French Population-based cohort study 12,336 Surgical < 22 wks Maternal age, parity, education, smoking SGA
Fox-Helias and Blondel, 2000 French Case-control 17,411 D&E N/A None PTB
Che et al, 2001 China Retrospective cohort 2707 Vacuum N/A Parental age, occupation, education, maternal BMI PTB
El-Bastawissi et al, 2003 United States Case-control 654 Surgical N/A Maternal age, race, smoking, parity PTB
Ancel et al, 2004 Europe Case-control 7721 Surgical N/A Maternal age, marital status, social class, smoking, parity PTB
Moreau et al, 2005 French Case-control 2561 Surgical N/A None PTB
Raatikainen et al, 2006 Finland Retrospective cohort 26,967 Vacuum < 14 wks Maternal age, weight, marital status, education, smoking, alcohol consumption, parity, uterine surgery N/A
Bhattacharya et al, 2012 Scotland Population-based cohort study 577,510 Vacuum N/A Maternal age, weight, smoking PTB
McCarthy et al, 2013 Multicenter Prospective cohort 4812 D&E N/A Maternal age, weight, smoking PTB
Woolner et al, 2014 Scotland Population-based cohort study 45,631 D&E N/A Smoking, social class PTB

D&E , dilatation and evacuation; GA , gestational age; LBW , low birth weight; N/A , data not reported in the original study; PTB , preterm birth; SGA , small for gestational age; Surgical abortion , both dilatation and evacuation and vacuum.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016.


Table 3

Characteristics of the included studies on medically induced termination of pregnancy








































Study Study location Type of study Number of included women Method of abortion GA at abortion Confounders adjusted Primary outcome
Zhu et al, 2009 China Prospective cohort 9363 200 mg mifepristone < 14 wks None Placental complications
Mirmilstein et al, 2009 Australia Prospective cohort 154 400 μg misoprostol 14-24 wks None PTB
Winer et al, 2009 France Prospective cohort 736 200 mg mifepristone followed by 400 μg misoprostol < 22 wks None PTB

GA , gestational age; PTB , preterm birth.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016.


Table 4

Characteristics of the included studies on spontaneous abortion


























































Study Study location Type of study Number of included women Method of abortion GA at abortion Confounders adjusted Primary outcome
Doyle 2000 Taiwan Case-control 12,273 Surgical N/A None PTB
Nguyen et al, 2004 Vietnam Case-control 1709 Surgical N/A None PTB
Smith et al, 2006 Scotland Population-based case-control 84,391 Surgical N/A None PTB
Selo-Ojeme and Tewari, 2006 United Kingdom Case-control 206 Surgical N/A None PTB
Freak-Poli et al, 2009 Australia Population-based case-control study 25,554 Surgical < 20 wks None N/A

D&E , dilatation and evacuation; GA , gestational age; LBW , low birth weight; N/A , data not reported in the original study; PTB , preterm birth; SGA , small for gestational age; Surgical abortion , either dilatation and evacuation or vacuum.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016.


The quality of the studies included in our metaanalysis was assessed by the Methodological Index for Non-Randomized Studies’ tool for assessing the risk of bias ( Figure 3 ). Nine of the included studies were retrospective cohorts, whereas 9 were prospective cohorts; 11 were case-control studies ; 7 were large, high-quality population-based studies. The majority had a low risk of bias in the aim and the time.




Figure 3


Assessment of risk of bias

A, Summary of the risk of bias for each study. Plus sign indicates a low risk of bias; minus sign indicates a high risk of bias; question mark indicates an unclear risk of bias. B, Risk of bias graph about each risk of the bias item presented as percentages across all included studies.

Aim , clearly stated aim; Bias , unbiased assessment of study endpoints; Data , prospective collection of data; Loss , loss to follow-up; Rate , inclusion of consecutive patients and response rate; Size , calculation of the study size; Time , follow-up time appropriate.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016 .


Synthesis of results


Uterine evacuation for induced termination of pregnancy or spontaneous abortion: combined data


In the overall population, women with a history of uterine evacuation for either I-TOP or SAB had a significantly higher risk of PTB (5.7% vs 5.0%; OR, 1.44, 95% CI, 1.09–1.90; Figure 4 A; 34 studies, 1,031,320 women), low birthweight (7.3% vs 5.9%; OR, 1.41, 95% CI, 1.22–1.62; Figure 4 B; 11 studies, 675,197 women), and small for gestational age (10.2% vs 9.0%; OR, 1.19, 95% CI, 1.01–1.42; Figure 4 C; 3 studies, 43,411 women) compared with controls (ie, women without a history of uterine evacuation).




Figure 4


Primary and secondary outcomes in women with uterine evacuation for induced termination of pregnancy or spontaneous abortion

Forest plot for primary outcome (ie, risk of preterm birth) and for secondary outcomes (ie, low birthweight, small for gestational age) in overall women with a history of uterine evacuation for either induced termination of pregnancy or spontaneous abortion. A, Risk for PTB. B, Risk for LBW. C, Risk for SGA.

CI , confidence interval; LBW , low birthweight; M-H , Mantel-Haenszel test; PTB , preterm birth; SGA , small for gestational age.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016 .


Induced termination of pregnancy


Of the 31 studies reporting data regarding I-TOP, 28 included 913,297 women with a history of surgical I-TOP, whereas 3 included 10,253 women with a prior medical I-TOP ( Tables 2 and 3 ). Women with a history of uterine evacuation for I-TOP had a significantly higher risk of PTB (5.5% vs 4.4%; OR, 1.52, 95% CI, 1.09–2.13; Figure 5 A, 29 studies, 907,187 women), low birthweight (7.3% vs 5.9%; OR, 1.41, 95% CI, 1.22–1.62; Figure 5 B; 11 studies, 675,197 women), and small for gestational age (10.2% vs 9.0%; OR, 1.19, 95% CI, 1.01–1.42; Figure 5 C; 3 studies, 43,411 women) compared with controls (ie, women without history of uterine evacuation for I-TOP).




Figure 5


Primary and secondary outcomes in induced termination of pregnancy

Forest plot for primary outcome (ie, risk of preterm birth) and for secondary outcomes (ie, low birthweight, small for gestational age) in women with a history of uterine evacuation for induced termination of pregnancy. A, Risk for PTB. B, Risk for LBW. C, Risk for SGA.

CI , confidence interval; I-TOP , induced termination of pregnancy; LBW , low birthweight; M-H , Mantel-Haenszel test; PTB , preterm birth; SGA , small for gestational age.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016 .


Surgically induced termination of pregnancy


Table 2 shows the characteristics of the included studies on surgical I-TOP. A total of 913,297 women from 28 studies with at least 1 prior surgical I-TOP were included. Seventeen studies reported information on confounders and adjusted risk estimates. Ten studies included only singleton gestations. The vast majority (27 of the 28) stratified data for number of prior I-TOP, whereas 1 did not report informative data about it.


Most of the studies had incidence of PTB as the primary outcome. Regarding the method of abortion, 5 studies defined the procedure as only VA, 5 studies defined the procedure as only D&E, whereas the others used both methods. One study reported the use of prostaglandins followed by D&E.


Women with a prior surgical I-TOP had a significantly higher risk of PTB (5.4% vs 4.4%; OR, 1.52, 95% CI, 1.08–2.16; Figures 6 A; 27 studies, 906,297 women), low birthweight (7.3% vs 5.9%; OR, 1.41, 95% CI, 1.22–1.62; Figure 6 B; 11 studies, 675,197 women), and small for gestational age (10.2% vs 9.0%; OR, 1.19, 95% CI, 1.01–1.42; Figure 6 C; 3 studies, 43,411 women) compared with controls (ie, women without a history of uterine evacuation for I-TOP).




Figure 6


Primary and secondary outcomes in uterine evacuation for surgically induced termination of pregnancy

Forest plot for primary outcome (ie, risk of preterm birth) and for secondary outcomes (ie, low birthweight, small for gestational age) in women with a history of uterine evacuation for surgically induced termination of pregnancy. A, Risk for PTB. B, Risk for LBW. C, Risk for SGA.

CI , confidence interval; I-TOP , induced termination of pregnancy; LBW , low birthweight; M-H , Mantel-Haenszel test; PTB , preterm birth; SGA , small for gestational age.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016 .


The risk of PTB was still significantly higher after adjusting for confounders statistically proven, including marital status, smoking, age, ethnicity, economic status, parity, maternal height, race, social class, gestational age at entry, gravidity, parity, parental age, education, body mass index, uterine surgery, type of work, alcohol consumption, urinary tract infection, and sex of the infant (aOR, 1.25, 95% CI, 1.13–1.38; Figure 7 ; 16 studies, 874,080 women).




Figure 7


Adjusted estimates for primary outcome in surgically induced termination of pregnancy

Adjusted estimates forest plot for primary outcome (ie, risk of preterm birth) in women with a history of surgically induced termination of pregnancy.

CI , confidence interval; IV , independent variable.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016 .


Subgroup analysis: method of abortion


Comparing the women with a prior surgical I-TOP with those who did not, both VA (3.6% vs 3.1%; OR, 1.20, 95% CI, 1.16–1.24; Figure 8 ; 5 studies, 609,912 women) and D&E (5.5% vs 4.3%; OR, 1.39, 95% CI, 1.08–1.80; Figure 9 ; 5 studies, 68,679 women) were associated with an increased risk of PTB. Moreover, by using an indirect comparison metaanalysis, we found that women who received D&E had a significantly higher risk of PTB compared with those who received VA (5.5% vs 3.6%; OR, 1.54, 95% CI, 1.38–1.73).




Figure 8


Primary outcome in surgically induced termination of pregnancy with vacuum aspiration

Forest plot for primary outcome (ie, risk of preterm birth) in women with a history of surgically induced termination of pregnancy with vacuum aspiration.

CI , confidence interval; I-TOP , induced termination of pregnancy; M-H , Mantel-Haenszel test; PTB , preterm birth; VA , vacuum aspiration.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016 .



Figure 9


Primary in surgically induced termination of pregnancy with dilatation and evacuation

Forest plot for primary outcome (ie, risk of preterm birth) in women with a history of surgically induced termination of pregnancy with dilatation and evacuation.

CI , confidence interval; D&C , dilatation and evacuation; I-TOP , induced termination of pregnancy; M-H , Mantel-Haenszel test; PTB , preterm birth.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016 .


Subgroup analysis: number of prior I-TOP


Women with only 1 prior surgical I-TOP had a significantly higher risk of PTB compared with those who did not have any prior I-TOP (5.1% vs 4.4%; OR, 1.53, 95% CI, 1.02–2.31; Figure 10 A; 23 studies, 875,356 women). Women with more than 1 prior surgical I-TOP had a significantly higher risk of PTB compared with those without any prior I-TOP (23.4% vs 8.6%; OR, 1.98, 95% CI, 1.46–2.68; Figure 10 B; 9 studies, 165,085 women). Moreover, by using an indirect comparison metaanalysis, we found that women with more than 1 prior surgical I-TOP had a significantly higher risk of PTB compared with those who had only 1 prior surgical I-TOP (23.4% vs 5.1%; OR, 5.65, 95% CI, 5.10–6.25).




Figure 10


Primary outcome of prior terminations of pregnancy in surgically induced termination of pregnancy

Forest plot for primary outcome (ie, risk of preterm birth) according to number of prior termination of pregnancy in women with history of surgically induced termination of pregnancy. A, Women with only 1 prior surgical I-TOP. B, Women with more than 1 prior surgical I-TOP.

CI , confidence interval; I-TOP , induced termination of pregnancy; M-H , Mantel-Haenszel test; PTB , preterm birth.

Saccone. Abortion and risk of preterm birth. Am J Obstet Gynecol 2016 .


Subgroup analysis: number of fetuses


In a subgroup analysis of studies in which only singleton gestations in the index pregnancy were enrolled, women with a history of surgical I-TOP had a significantly higher risk of PTB compared with controls (9.6% vs 6.6%; OR, 1.45, 95% CI, 1.27–1.65; Figure 11 ; 10 studies, 152,668 women). No separate data about multiple gestations were reported in any studies.


May 4, 2017 | Posted by in GYNECOLOGY | Comments Off on Prior uterine evacuation of pregnancy as independent risk factor for preterm birth: a systematic review and metaanalysis

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