Sexual intercourse frequency and fecundability in the Norwegian mother, father and child cohort study
5 affiliations
- 1Fertility department, Telemark Hospital, Porsgrunn, Norway
- 2Centre for Fertility and Health, Norwegian Institute of Public Health, Oslo, Norway
- 3Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
- 4Department of Gynecology and Obstetrics, Vestfold Hospital, Tønsberg, Norway
- 5Department of Public Health, Aarhus University, Aarhus, Denmark
Abstract
Objective: The aim of this study was to explore the association between frequency of intercourse in the four weeks leading up to conception and fecundability among women trying to conceive in a pregnancy cohort. Methods: The Norwegian Mother, Father and Child Cohort Study is a pregnancy cohort in Norway with recruitment between 1999 and 2008. This study includes self-reported questionnaire data from 64 193 women with planned, naturally conceived pregnancies. Results: The mean time to pregnancy decreased with intercourse frequency from 4.8 months for less than once per week to 3.7 months for > 4 times weekly, however the decrease was primarily evident for the group reporting intercourse > 4 times weekly compared to lower intercourse frequencies. There was a significant trend in TTP across ordered intercourse frequency groups (p < 0.0001), indicating progressively shorter TTP with higher intercourse frequencies. We found a 16% higher chance of conceiving in any cycle (fecundability ratio 1.16 (95% CI:1.14–1.19)) among women reporting intercourse >4 times per week compared to the reference group (1–2 times per week) within the analytic cohort. This association was consistent in supplementary analyses accounting for BMI, parity, menstrual cycle regularity and endometriosis. There were no clear differences in fecundability between intercourse frequencies of less than once, 1–2 and 3–4 times per week. Conclusion: Among women with planned pregnancies that resulted in natural conception, intercourse >4 times per week in the four weeks leading up to conception, was associated with a higher cycle probability of conceiving, whereas differences across lower frequency categories were limited.
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BibTeX
@article{dreias2026sexual,
title = {{Sexual intercourse frequency and fecundability in the Norwegian mother, father and child cohort study}},
author = {Kristina W. Dreiås and Liv G. Kvalvik and Mari L. Warp and Siri E. Håberg and Cecilia H. Ramlau-Hansen and Hans Ivar Hanevik},
journal = {PLOS One},
year = {2026},
month = sep,
doi = {10.1371/journal.pone.0357286},
url = {https://doi.org/10.1371/journal.pone.0357286},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Sexual intercourse frequency and fecundability in the Norwegian mother, father and child cohort study
AU - Kristina W. Dreiås
AU - Liv G. Kvalvik
AU - Mari L. Warp
AU - Siri E. Håberg
AU - Cecilia H. Ramlau-Hansen
AU - Hans Ivar Hanevik
PY - 2026
DA - 2026/09/23
JO - PLOS One
DO - 10.1371/journal.pone.0357286
UR - https://doi.org/10.1371/journal.pone.0357286
AB - Objective: The aim of this study was to explore the association between frequency of intercourse in the four weeks leading up to conception and fecundability among women trying to conceive in a pregnancy cohort. Methods: The Norwegian Mother, Father and Child Cohort Study is a pregnancy cohort in Norway with recruitment between 1999 and 2008. This study includes self-reported questionnaire data from 64 193 women with planned, naturally conceived pregnancies. Results: The mean time to pregnancy decreased with intercourse frequency from 4.8 months for less than once per week to 3.7 months for > 4 times weekly, however the decrease was primarily evident for the group reporting intercourse > 4 times weekly compared to lower intercourse frequencies. There was a significant trend in TTP across ordered intercourse frequency groups (p < 0.0001), indicating progressively shorter TTP with higher intercourse frequencies. We found a 16% higher chance of conceiving in any cycle (fecundability ratio 1.16 (95% CI:1.14–1.19)) among women reporting intercourse >4 times per week compared to the reference group (1–2 times per week) within the analytic cohort. This association was consistent in supplementary analyses accounting for BMI, parity, menstrual cycle regularity and endometriosis. There were no clear differences in fecundability between intercourse frequencies of less than once, 1–2 and 3–4 times per week. Conclusion: Among women with planned pregnancies that resulted in natural conception, intercourse >4 times per week in the four weeks leading up to conception, was associated with a higher cycle probability of conceiving, whereas differences across lower frequency categories were limited.
SN - 1932-6203
ER -