Estimating the risk of adverse birth outcomes in pregnant women undergoing non-obstetric surgery using routinely collected NHS data: an observational study

Abstract

Background: Previous research suggests that non-obstetric surgery is carried out in 1 – 2% of all pregnancies. However, there is limited evidence quantifying the associated risks. Furthermore, of the evidence available, none relates directly to outcomes in the UK, and there are no current NHS guidelines regarding non-obstetric surgery in pregnant women. Objectives: To estimate the risk of adverse birth outcomes of pregnancies in which non-obstetric surgery was or was not carried out. To further analyse common procedure groups. Data Source: Hospital Episode Statistics (HES) maternity data collected between 2002 – 3 and 2011 – 12. Main outcomes: Spontaneous abortion, preterm delivery, maternal death, caesarean delivery, long inpatient stay, stillbirth and low birthweight. Methods: We utilised HES, an administrative database that includes records of all patient admissions and day cases in all English NHS hospitals. We analysed HES maternity data collected between 2002 – 3 and 2011 – 12, and identified pregnancies in which non-obstetric surgery was carried out. We used logistic regression models to determine the adjusted relative risk and attributable risk of non-obstetric surgical procedures for adverse birth outcomes and the number needed to harm. Results: We identified 6,486,280 pregnancies, in 47,628 of which non-obstetric surgery was carried out. In comparison with pregnancies in which surgery was not carried out, we found that non-obstetric surgery was associated with a higher risk of adverse birth outcomes, although the attributable risk was generally low. We estimated that for every 287 pregnancies in which a surgical operation was carried out there was one additional stillbirth; for every 31 operations there was one additional preterm delivery; for every 25 operations there was one additional caesarean section; for every 50 operations there was one additional long inpatient stay; and for every 39 operations there was one additional low-birthweight baby. Limitations: We have no means of disentangling the effect of the surgery from the effect of the underlying condition itself. Many spontaneous abortions will not be associated with a hospital admission and, therefore, will not be included in our analysis. A spontaneous abortion may be more likely to be reported if it occurs during the same hospital admission as the procedure, and this could account for the associated increased risk with surgery during pregnancy. There are missing values of key data items to determine parity, gestational age, birthweight and stillbirth. Conclusions: This is the first study to report the risk of adverse birth outcomes following non-obstetric surgery during pregnancy across NHS hospitals in England. We have no means of disentangling the effect of the surgery from the effect of the underlying condition itself. Our observational study can never attribute a causal relationship between surgery and adverse birth outcomes, and we were unable to determine the risk of not undergoing surgery where surgery was clinically indicated. We have...

Treatment of tubal heterotopic pregnancy with viable intrauterine pregnancy: a retrospective study

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“…No statistical differences were observed for estimated blood loss, surgical type, timing of surgery, gestational age, resection of fallopian tube, operation time and abortion rate in the subgroup analyses. Although the risk of adverse pregnancy outcomes associated with surgery during pregnancy was low, data from several large-scale retrospective observational studies found that the risk of abortion was higher in patients with nonobstetric abdominal surgery during pregnancy [18][19][20]. In our study, the abortion rate in the surgical treatment group (7/42, 16.67%) was higher than that in the expectant treatment group (2/28, 7.14%), similar to the above studies.…”

Risk of Adverse Fetal Outcomes Following Nonobstetric Surgery During Gestation: A Nationwide Population-Based Analysis

“…[6] A large scale study in the United Kingdom used National Health Service data to estimate the risk of adverse birth outcomes in pregnant women undergoing nonobstetric surgery and observed an increased risk of miscarriage, preterm labour, low birth weight, and caesarean section. [7] Another nationwide sampling case-control study reported increased rates of spontaneous abortion, caesarean section rate, and preterm labour following nonobstetric surgery during gestation. [5] A Danish registry-based cohort study reported that nonobstetric abdominal surgery during pregnancy was associated with an increased risk of adverse birth outcomes, including small for gestational age, preterm labour, and miscarriage.…”

National data opt out programme: consequences for maternity services in England

“…Using maternity data from HES linked with data from each maternity unit, the NMPA provides a range of statistics comparing outcomes at maternity unit level, including induction of labour and caesarean section rates. In addition, HES has been used for maternal and child health research to examine, for example, factors explaining excess child mortality in England and the safety of surgical procedures during pregnancy [19,20]. Individual level data are necessary for this type of research, since this allows multiple risk factors for maternal and child outcomes to be taken into account.…”