The risk of a poor perinatal outcome is higher among male twins than their female co-twins. This was the conclusion of a recent study published in August 2017. Researchers aimed to explore gender differences in infant mortality and neonatal morbidity in boy/girl twin pairs. A total of 108,038 pairs of boy/girl twins were included in the analysis. Data were obtained from the US National Center for Health Statistics Linked Birth-Infant Death Cohort. The birth data information contain information on multiple births that occurred from 1995–2004 in the United States.
Low Apgar score
Male twins had an increased risk of neonatal mortality and overall infant mortality relative to their female co-twins. Congenital abnormalities were identified significantly more frequently in male than female twins. Male twins also had higher risk of having a low 5-minute Apgar score* and Respiratory Distress Syndrome. The researchers didn’t find a significant difference in fetal mortality among female twins and their male co-twins.
*The Apgar score is an assessment of how a baby is doing at birth. Immediately after birth, the midwife or doctor assesses how a baby is doing and whether or not medical assistance is needed. The highest score is 10. Many children have an Apgar, which is less than 10, and develops well anyway.