INCIDENCE OF ECTOPIC PREGNANCY AMONG PEOPLE SEEKING AND NOT SEEKING ABORTION IN A LARGE INTEGRATED HEALTHCARE DELIVERY SYSTEM: A CASE-CONTROL STUDY

Objectives

We aimed to compare the incidence of ectopic pregnancy, associated risk factors, and presentation to care among people seeking and not seeking abortion, using a retrospective case-control study.

Methods

We selected a random sample of 2,201 ectopic and 1,153 intrauterine pregnancies (out of 385,081 pregnancies) of people enrolled at Kaiser Permanente Northern California from 2016-2021. We reviewed electronic health records to classify pregnancies as seeking or not seeking abortion and to obtain medical history. We used logistic regression analyses weighted to the total pregnancy pool (n=385,081) to assess incidence of ectopic pregnancies, associated risk factors, and whether risk factors accurately identify people with ectopic pregnancies.

Results

The adjusted incidence of ectopic pregnancy was lower for people seeking abortion (0.39%) than for people not seeking abortion (1.74%, p<0.001). People seeking abortion were less likely to present with bleeding symptoms (53% and 64%, p<0.01), equally likely to present with unilateral pain (35% and 35%) and received more timely care than people not seeking abortion, including fewer encounters until diagnosis (2.2 vs 2.6, p<0.001) and earlier treatment for ectopic pregnancy (53 days gestation vs 55 days, p<0.05). Among people seeking abortion (n=511), history of IUD use, ectopic pregnancy, and tubal surgery, together identified 12.7% (sensitivity) of ectopic cases, with 93.5% specificity, and a 55.5% area under the receiver operating characteristic (AUROC).

Conclusions

People seeking abortion are at lower risk of ectopic pregnancy and receive more timely ectopic care than those not seeking abortion. History-based screening in abortion care may not accurately distinguish people with and without ectopic pregnancy.