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The seasonality of conception
Ester Lucia Rizzi1, Gianpiero Dalla-Zuanna
1Department of Statistics, University of Messina, Italy.
Demography
|February 1, 2008
Summary
Biological seasonality of conception persists in women, influenced by age and intercourse frequency. Conception probability shows seasonal patterns, with peaks in September and January, even after controlling for sexual behavior.
Area of Science:
- Human Reproduction
- Reproductive Endocrinology
- Demography
Background:
- Biological seasonality in conception has been observed, but its persistence after controlling for sexual behavior is unclear.
- Understanding factors influencing conception seasonality is crucial for reproductive health and population studies.
Purpose of the Study:
- To investigate if the biological seasonality of conception persists in non-contracepting women after accounting for sexual behavior.
- To examine the influence of age and frequency of intercourse on conception seasonality.
Main Methods:
- Analysis of individual menstrual cycle data from non-contracepting women in Western countries.
- Daily recording of intercourse episodes and detection of ovulation using a marker.
- Statistical control for sexual behavior and age-related factors.
Main Results:
- Conception seasonality varies with a woman's age and the frequency of sexual intercourse.
- For women aged 27-31 with infrequent intercourse, conception seasonality (fecundability) is more pronounced.
- After controlling for sexual intercourse seasonality, conception probability exhibits a bimodal distribution with peaks in September and January.
Conclusions:
- The seasonal pattern of conception persists even when controlling for sexual behavior and considering unobserved couple characteristics.
- Age and frequency of intercourse are significant modulators of conception seasonality.
- Seasonal variations in conception probability highlight the interplay between biological and behavioral factors in human reproduction.
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