O-216 Sex, smoking, age and natural fecundity: results of a survey performed on 2510 puerperal women and their partners
Authors: Limia Pérez M I , Matorras Weining R 
Published: June 2023

Abstract

Study question
Sex, smoking, age and natural fecundity: results of a survey performed on 2510 puerperal women and their partners.

Summary answer
We reported that the best fertility marker was amongst couples who had 7 intercourses per week.

What is known already
Most reproductive scientific societies recommend that infertility studies begin after 12 months of unprotected intercourse without pregnancy. There is a series of parameters whose influence on assisted reproduction has been extensively studied, but which have received little attention when studying natural fertility. For example, it is well known that human fertility is strongly related to female age and that there is a decline in ART success rates with increasing woman's age. Also smoking has been reported to decrease fertility in women, both in natural fertility and in ART cycles.

Study design, size, duration
The aim of our study was:
1) to analyze the cumulative fecundity rate (CFR), the per month fecundity rate (FR) and the time to pregnancy (TTP).
2) to ascertain the influence of woman and male age, smoking, previous fertility and frequency of sexual intercourse in the aforementioned fecundity markers.

Participants/materials, setting, methods
The study population consisted of 2510 puerperal women and their partners whose labor was performed at our Hospital. During a 12-month period, an anonymous survey was performed during hospital admission, within 36-72 hours postpartum. The survey was offered to all postpartum women, although only those who met the inclusion criteria were analyzed.

Main results and the role of chance
- There was a close correlation between woman’s age and male’s age (Pearson coefficient= 0.72, p &lt; 0.00001). When the age of one partner was considered independently of the age of the other there was no correlation between woman’s age and TTP (Person coefficient = 0.04, p = 0.08) or between man’s age and TTP (Person coefficient = 0.02, p = 0.38).
- There was a significant correlation between TTP (time to pregnancy) and man’s age (Pearson coefficient= 0.07, p = 0.0006).
- We observed a significantly higher fecundity rate (FR) at the first month and a significantly higher cumulative fecundity rate (CFR) at 3 and 6 months in non smokers. Moreover we found a significant correlation with the number of cigarettes smoked and the TTP. It has to be highlighted that in our study the fertility impact of smoking was remarkably higher in men than in women.
- Pregnancy rates were similar, independently the existence or not of previous pregnancies.
- Regardless of coital frequency and natural fertility, our study revelaed two remarkable facts, one related with infrequent intercourse and the other regarding frequent. The best fertility marker among the couples was reported a 7 per week coital frequency.

Limitations, reasons for caution
- Only couples reaching pregnancy were studied.
- Second hand smoking was not considered.
- Possible inaccuracy because at long-term recall, TTP may sometimes only be estimated roughly by couples completing the questionnaire.
- Assumption that it is only one cycle per month.
- Misscariages were not taken into account.

Wider implications of the findings
Our results challenge the widely accepted idea that among healthy women trying to conceive, nearly all pregnancies can be attributed to intercourse during a 6-day period ending on the day of ovulation. We reported that the best fertility marker was amongst couples who had 7 intercourses per week.

Trial registration number
Not applicable