Purpose Higher risk for birth of singletons being large for gestational age (LGA) has been revealed after in vitro fertilization (IVF) frozen-thawed embryo-transfer (FET). This phenomenon is now being investigated, since there is a speculation that these neonates could suffer from underlying epigenetic disturbances. The aim of the study was to expose independent LGA risk factors and to identify those connected to the IVF techniques. Methods Altogether, 4508 singleton pregnancies and births were included in the cohort case-matched study. Two hundred eleven singleton pregnancies and births after FET and 916 after fresh embryo transfer (ET) were included into two study groups. The IVF procedures were performed at the University Medical Centre Ljubljana between 2004 and 2011. For each IVF pregnancy, three matched consecutive controls after natural conception were included. Using logistic regression models, we observed LGA connection to maternal parameters (smoking, hypertension, parity, BMI, gestational diabetes, IVF conception, FET, double ET, and ICSI procedure).Results Singletons born after FET had a significantly higher risk for being LGA (p=0.032; OR 1.697; 95 % CI 1.047-2.752). BMI 25-30 was a significant independent risk factor for LGA in the IVF groups (FET p=0.041, OR 2.460, 95 % CI 1.030-5.857 and fresh ET p=0.003; OR 2.188, 95 % CI 1.297-3.691). ICSI and double ET had no significant effect on LGA occurrence. Conclusions Besides maternal BMI, FET is a significant independent LGA risk factor in IVF patients. Other observed factors (smoking, hypertension, multiparity, GDM, ICSI procedure, or number of embryos transferred) do not influence LGA risk significantly.

Pre-gravid BMI is more strongly associated with preeclampsia and GDM in twin and singleton pregnancies than gestational BMI change. Smaller gestational BMI change in GDM pregnancies reflect the importance of dietary counseling.

The incidence of iatrogenic preterm birth is increasing with a concomitant decrease in the incidence of spontaneous preterm birth. Attempts to analyze, interpret and decrease preterm birth rates should consider spontaneous and iatrogenic preterm births separately.

Objective To compare perinatal outcomes before and after implementation of the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria for testing of gestational diabetes mellitus (GDM). Methods A national, perinatal, registry‐based cohort study of prospectively collected data was conducted. Patients with diabetes type 1 or 2 were excluded. Outcomes of 135 786 pregnancies before (January 1, 2004 to May 31, 2010) and 140 524 after (June 1, 2011 to December 31, 2017) the introduction of IADPSG criteria were compared using Student t test and χ2 test (P<0.05 was significant). Multivariable logistic regression was used to compare outcomes controlling for potential confounders. Results Prevalence of GDM increased from 2.6% to 9.7% (adjusted odds ratio 3.92; 95% confidence interval 3.78–4.08). Incidence of large‐for‐gestational age (LGA), macrosomia (birth weight >4500 g), Erb's palsy, and hypertensive disorders in pregnancy decreased despite increasing maternal age and pre‐pregnancy obesity. Rates of cesarean delivery increased in both GDM and non‐GDM groups, with a less pronounced increase in GDM mothers. Incidence of small‐for‐gestational age (SGA) increased in GDM but not in non‐GDM group. Conclusion Implementation of IADPSG criteria in a country with a relatively low prevalence of GDM did not result in higher rates of cesarean delivery and was associated with reductions in LGA and hypertensive disorders in pregnancy.

GDM, per se, is not a major contributor to RDS in late pre-term infants. Rather, the combination of prematurity and cesarean birth act independently to increase the risk of respiratory morbidity.