DOES IN-VITRO FERTILIZATION AFFECT INTER-DELIVERY INTERVAL IN PATIENTS WITH RECURRENT PREGNANCY LOSS? A POPULATION STUDY

Abstract

This study aimed to compare the interval to second live birth in women with recurrent pregnancy loss (RPL) who required IVF to those who conceived spontaneously. This retrospective study included women with live births in 2008-2018 from the British Columbia Perinatal Data Registry. This provincial registry collected perinatal variables from the mandatory reporting of all attended births. The cohort included RPL women with 2 recorded live births and were nulliparous at first delivery. The time interval was compared using a log-logistic survival model, controlling for factors such as age, BMI, city of residence, and number of miscarriages. There were 9503 women with RPL and 2 recorded deliveries; 4% of which required IVF to conceive the second child. IVF use was associated with older maternal age at first delivery (age 33.8 vs 28.9), previous IVF use (38.7% vs 1.5%), primary RPL (38.14% vs 28.73%), and higher number of miscarriages before the second delivery (2.64 vs 2.25) compared to those who conceived spontaneously (P all < 0.0001). In the unadjusted analysis, the duration from first delivery to second birth was significantly longer in those who required IVF compared to the control group, 4.1 and 3.8 years respectively (P = 0.0002). After adjustment, those who required IVF had a longer interval to second birth among younger women, but this difference was attenuated among older women. There was no significant difference in the time to second delivery after IVF use compared to spontaneous conception in RPL patients ≥ 35 years old at first birth. However, the study showed that younger women who conceived the second child with IVF had a longer inter-delivery interval. This may be related to underlying differences in infertility diagnosis and/or family planning.