Introduction:
Twinning rates were subject to many changes in the past few decades, almost doubling between 1980 – 1985 and 2010 – 2015. This is mainly due to increasing rates of assisted reproductive technology (ART) and increasing maternal age, the latter being accompanied by a higher likelihood for multiple pregnancies. In addition, a body mass index (BMI) ≥30 kg/m2 is associated with a higher risk for twin pregnancies. With the prevalence of obese people worldwide almost tripling in the last three decades, it is no surprise that twinning rates rise in the context with increasing overweight and obesity incidences.
Although the relationship between maternal weight and the likelihood for twins has been investigated, the risks of overweight and obesity on fetomaternal outcomes have been subject to only few studies, especially regarding the impact of the three obesity classes as defined by the WHO. In singleton pregnancies, overweight and obesity lead to a 18 – 47% higher risk for obstetric complications.
The incidence of overweight and obese women of child-bearing age in Germany is at a distressing level. Thus, this study aims to examine the impact of maternal weight and especially obesity on fetomaternal complications and outcomes in twin pregnancies, hypothesizing that an increasing BMI and an increasing obesity class lead to a higher likelihood for adverse fetomaternal outcomes.