Peripartum and postpartum outcomes in uncomplicated term pregnancy following ART: a retrospective cohort study from two Italian obstetric units

STUDY QUESTION: Do singleton uncomplicated term pregnancies conceived by assisted reproductive technology (ART) have adverse peripartum and postpartum outcomes? SUMMARY ANSWER: Term pregnancies following ART, even if uncomplicated until birth, have a higher risk of retained placenta and postpartum hemorrhage (PPH). WHAT IS KNOWN ALREADY: There is consistent evidence that pregnancies following ART have higher incidence of complications during pregnancy. However, few studies specifically investigated birth outcomes in ART term pregnancies. STUDY DESIGN, SIZE, DURATION: A retrospective cohort study was conducted on 14 415 deliveries at two university tertiary care obstetric units. Clinical data were extracted by reviewing obstetric records of all deliveries from 1 January 2010 to 31 December 2014, in a standardized electronic database regarding the mother's health before and during pregnancy, complications during pregnancy and at birth, and neonatal outcome. PARTICIPANTS/MATERIALS, SETTING, METHODS: Following an accurate evaluation of exclusion criteria (multiparity, maternal pre-pregnancy diseases, prior uterine surgery, fetal malformations, intrauterine deaths, elective cesarean section and pregnancy complications), the group of uncomplicated singleton term pregnancies from autologous ART conception by in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) (n = 188) was compared with a maternal age and body mass index (BMI) matched group of spontaneous pregnancies (n = 1168). Cases of intrauterine insemination (IUI) (n = 14) and ovulation induction with timed intercourse (n = 18) were not included. Labor, delivery and postpartum outcomes were evaluated. Odds ratios (OR) were adjusted with multivariable logistic regression to maternal age, BMI, nationality and gestational age at birth. MAIN RESULTS AND THE ROLE OF CHANCE: The age of women in the final analysis ranged from 25 to 45 years, while BMI ranged from 17 to 34 kg/m(2). Uncomplicated term pregnancies with ART conception had a higher risk of operative delivery (adjusted OR 1.40, 95% confidence interval (CI) 1.01-1.95), retained placenta (adjusted OR 2.63, 95% CI 1.31-5.26) and PPH (adjusted OR 2.86 95% CI 1.37-5.99). Conversely, ART conception did not increase the risk of induced labor (adjusted OR 1.18, 95% CI 0.85-1.65). However, patients that conceived by ART and underwent labor induction had a higher risk of failed induction compared with the control group (adjusted OR 2.53, 95% CI 1.23-5.21). Infants born after ART had a similar birthweight, Apgar score and arterial blood pH compared with spontaneously-conceived ones. LIMITATIONS, REASONS FOR CAUTION: The database lacked specific information about causes of infertility, smoking habit, family income and details on ART (fresh versus frozen cycle, IVF versus ICSI), limiting, in part, our analysis of the results. However, only autologous IVF/ICSI pregnancies were included in order to prevent bias related to conception by oocyte/embryo donation. In vivo conception ART cases were excluded because they were too few to allow comparison with IVF/ICSI. Nevertheless, the inclusion of only uncomplicated pregnancies provides a highly homogeneous and still representative population sample. Study sample is representative of a well-resourced obstetric facility in a high-income country, limiting to some extent the generalizability of study results. WIDER IMPLICATIONS OF THE FINDINGS: Pregnancies conceived by autologous ART that proceed uncomplicated until term may require counseling about the risk of placental retention with PPH.