Multiple pregnancies are challenging issues in pregnancy care and delivery planning. Due to the advances in reproductive medicine the number of multiple pregnancies increases from 14,9% in 2016 to 19.2% in 2018 within artificial reproductive technology (ART) cycles [1,2]. In the United States 25.5% of pregnancies were twins conceived with (ART) in 2017 [3]. 70% of multiple pregnancies are dichorionic and diamniotic (DC/DA) derived from two different fertilized ova [4]. Multiple pregnancies are more likely to be at risk for spontaneous and iatrogenic preterm births. 60% of all twins are born before 37 weeks of gestation, 12% between 37 and 32 weeks of gestation (WOG) [5]. Prematurity is associated with a variety of complications, such as respiratory distress syndrome (RDS), sepsis, necrotizing enterocolitis (NEC), and cerebral palsy [6]. These morbidities depend significantly on the gestational age [7]. Complications in multiple pregnancies comprise premature labor, premature rupture of membranes, intrauterine growth restrictions, and intrauterine death. Perinatal mortality in developed countries is 47 to 120 per 1000 twin births and 93 to 203 per 1000 triple births [8].

In cases of early preterm labor, not necessarily both twins must be delivered at the same time, therefore minimizing morbidity due prematurity for the remaining twin. Delayed-interval delivery (DID) of the second twin was first described in 1880, with an interdelivery interval of 44 days [9]. Another case report with 35 days interval was published in 1957 [10].

In addition to a variety of single case reports, larger case studies describe protocols to delay the delivery and improve the outcome of the second twin [6,[11], [12], [13], [14], [15], [16]]. However, to date there is no standardized treatment protocol or guideline on this approach. There are no randomized control trials [7]. In addition, it is not clear if this attempt is associated with an improvement of the long-term outcome of the second-born twin.

In the present study, the delayed-interval deliveries of 16 twin and one triplet pregnancy at one maternal-fetal medicine center are evaluated according to prolongation interval, treatment, maternal and fetal morbidity, and mortality, as well as outcome at the age of two years of the surviving children. The aim of the presented data is to evaluate the feasibility and safety of this method, including the long-term outcome of the surviving children in consideration of maternal morbidity and mortality.