Stillbirth and neonatal mortality in monochorionic and dichorionic twins: a population-based study

Area of Science:

• Perinatal Epidemiology
• Maternal-Fetal Medicine
• Twin Gestation Studies

Background:

• Chorionicity is a key determinant of perinatal mortality in twin pregnancies.
• Understanding mortality differences by chorionicity is crucial for improving twin outcomes.

Purpose of the Study:

• To analyze stillbirth and neonatal mortality rates by cause and chorionicity in twins.
• To quantify the risk of stillbirth by gestational age in dichorionic (DC) and monochorionic (MC) twins.

Main Methods:

• Utilized data from a large population-based twin registry in Northern England (1998-2007).
• Calculated prospective risk of stillbirth by gestational age using recorded fetal deaths.
• Compared mortality rates between MC and DC twins.

Main Results:

• Monochorionic twins exhibited significantly higher stillbirth (44.4/1000) and neonatal mortality (32.4/1000 live births) rates than dichorionic twins.
• Relative risks for stillbirth and neonatal mortality were 3.6 and 1.5, respectively, favoring DC twins.
• No significant improvements in mortality rates were observed for either group over the study period.
• The prospective risk of antepartum stillbirth was substantially higher for MC twins across all preterm gestations, peaking before 28 weeks.

Conclusions:

• Monochorionic twins experience disproportionately higher stillbirth and neonatal mortality rates compared to dichorionic twins.
• Mortality rates in twins did not show improvement from 1998 to 2007.
• The risk of antepartum stillbirth is markedly elevated in monochorionic twins at all gestational ages.