Advanced Parental Age and Wide Age Gap Effects on Human Secondary Sex Ratio in Romania

Simona-Mihaela Iftimie, MSc (
Bucharest University of Economic Studies, Romania


This paper aims to analyze the effects of parental age (especially advanced parental age) and age difference between parents on the probability of having a male/female offspring. The rationale of choosing this topic is based on the tendency of women to give birth at advanced age (>=35 years) and the increased frequency of couples with wide age gap. In order to conduct a successful research the data was obtained via survey, administrated online to the largest community of mothers in Romania. Using logistic regression models and statistical analysis we highlight the influence of maternal age, paternal age and the age gap on offspring gender. The paper brings new empirical evidence that advanced maternal age can shift the sex ratio in favor of male offspring and that a wide age gap between parents have influence on offspring’s gender. The study is outstanding since the literature regarding the subject worldwide is conflicting and the one regarding Romania is very poor or nonexistent.

Keywords: sex ratio, survey, logistic regression, advanced maternal age, age gap
JEL Classification: C53, C83, J13

[Full Text]

Romanian Statistical Review 2/2019