The factors that influence twinning rates

Area of Science:

• Reproductive Biology
• Human Genetics
• Epidemiology

Background:

• Twinning rates exhibit significant geographical and ethnic variations.
• Maternal age and parity are known factors influencing dizygotic (DZ) twinning rates.
• The role of hormonal factors, such as follicle-stimulating hormone (FSH), in twinning requires further investigation across diverse populations.

Purpose of the Study:

• To compare dizygotic (DZ) and monozygotic (MZ) twinning rates between a Nigerian and a Caucasian population.
• To identify demographic, social, and hormonal factors associated with twinning incidence in these populations.
• To investigate the relationship between maternal serum FSH levels and twinning rates in different ethnic groups.

Main Methods:

• Comparative study of twinning rates in Western Nigeria and Aberdeen, Scotland.
• Analysis of demographic data including maternal age, parity, height, social class, and ethnicity.
• Measurement of maternal serum FSH levels in twin-prone and non-twin-prone women from both populations.

Main Results:

• DZ twinning rates varied significantly with maternal age and parity, while MZ rates remained constant.
• Peak DZ twinning occurred in younger mothers (30-34 years) in Nigeria and older mothers (35-39 years) in Aberdeen.
• Higher maternal serum FSH levels were observed in the Nigerian population, correlating with higher twinning incidence and specifically in twin-prone Nigerian women.

Conclusions:

• Maternal age, parity, and serum FSH levels are key determinants of DZ twinning rates, with significant ethnic variations.
• Elevated maternal serum FSH levels likely contribute to the higher twinning incidence observed in the Nigerian population.
• Factors such as maternal height, social class, ethnicity, and illegitimacy also play a role in modulating DZ twinning rates in specific populations.