Observational studies using case control and cohort designs that reported one or more of the pre-specified primary and/or secondary outcomes for maternal age <35 (control) and ≥35 years (AMA) populations were included. Primary outcomes were stillbirth (according to individual study gestational age cut off) and fetal growth restriction (FGR) defined as birthweight below 5th centile adjusted for gestational age [17 (link)] Secondary outcomes were neonatal death (NND), small for gestation age (SGA; defined as a birthweight below 10th centile adjusted for gestational age or related definitions specified by authors), neonatal intensive care unit (NICU) admissions and neonatal acidosis (umbilical artery pH <7.0–7.2), preeclampsia (blood pressure ≥140/90 with significant proteinuria or as classified by authors where definition was not provided), placental abruption (classified by authors), preterm birth (PTB) <37 weeks gestation and gestational diabetes mellitus (GDM). Where authors stated different definitions of outcomes, data were re-classified in line with definitions stated (e.g. if authors defined FGR as <10th Centile this was re-classified as SGA in these analyses). Where definitions of classifications were not stated, authors’ classifications were accepted. Where possible, extracted data was sub-divided by parity (primiparous and multiparous mothers). Where reported, data regarding the frequency of maternal co-morbidities (obesity, hypertension and diabetes) and use of ART were extracted.
Duplicate studies were removed and the papers were excluded if they: were case reports, were restricted to multiple pregnancies or did not separate data from multiple pregnancies from singletons, primarily reported the success rates of assisted reproductive technologies or pre-existing medical conditions as a primary outcome, focused on chromosomal abnormalities or substance abuse, relevant data could not be extracted or were review papers. Reports on rising Cesarean section rates with AMA were not included as a systematic review was recently conducted on this topic [12 (link)] The initial search was conducted by one investigator (SL) and validated by a secondary conductor (HD) to ensure accuracy of search and application of exclusion criteria.
Duplicate studies were removed and the papers were excluded if they: were case reports, were restricted to multiple pregnancies or did not separate data from multiple pregnancies from singletons, primarily reported the success rates of assisted reproductive technologies or pre-existing medical conditions as a primary outcome, focused on chromosomal abnormalities or substance abuse, relevant data could not be extracted or were review papers. Reports on rising Cesarean section rates with AMA were not included as a systematic review was recently conducted on this topic [12 (link)] The initial search was conducted by one investigator (SL) and validated by a secondary conductor (HD) to ensure accuracy of search and application of exclusion criteria.
Free full text: Click here
