Objective
Increasing
age at first childbirth has been suggested to increase the risk for
infertility. Our objective is to determine whether women above thirty years of
age historically have been able to sustain fertility rates above replacement
level.
Design
A
descriptive nationwide Danish study using birth registries from 1901–2014.
Setting
Information
on women’s age at childbirth was obtained by using records from primary,
secondary and tertiary institutions.
Participants
Mothers
to 8,024,969 live births.
Main outcome measures
Mothers
were stratified according to age at childbirth to determine total and age
specific fertility rates.
Results
Total
fertility rate (TFR) decreased from 4.1 to 1.8 children per woman and age
specific fertility also decreased from 1901 to 2014. Women aged 30–34, 35–39 or
40–44 years in the first decade of the 20th century had higher fertility rates
than the corresponding five year younger age groups (25–29, 30–34 and 35–39,
respectively) have had for the last 65 years. On average, women gave birth to
two children after the age of 30 and one or more child after 35 years of age in
the beginning of the 1900s. Furthermore, women more than 40 years of age
accounted for 10% of TFR in 1901 compared with 4% in 2014 despite usage of
assisted reproduction.
Conclusion
This nationwide study shows that women above 30 years of
age historically have been able to sustain fertility rates above replacement
level. This implies that other factors besides age are strong determinants of
fertility in women above 30 years of age.
Below: A: Average maternal age at childbirth 1901–2014 and at first
childbirth 1960–2014. B: Total fertility rate (TFR) and cumulative fertility
rates for selected age groups 1901–2014
Below: A: Age specific fertility rates 1901–2014. B: Age specific
fertility rate 1901–2014. C: Age specific contribution to total fertility rate
1901–2014. D: Cumulative age specific fertility rates 1901–2014
Below: A: Legal Abortions 1981–2013. B: Age specific fertility
rates and estimated pregnancy rates including legal abortions (broken lines)
1993–2013
Full article at: http://goo.gl/50sfeM
By:
Department of Oral Medicine,
Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, United
States of America
Martin Blomberg Jensen, Lærke Priskorn, Tina Kold Jensen,
Anders Juul, Niels Erik Skakkebaek
Department of Growth and
Reproduction and International Research and Research Training Centre in
Endocrine Disruption of Male Reproduction and Child Health (EDMaRC),
Rigshospitalet, Faculty of Medical and Health Sciences, University of
Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark
More at: https://twitter.com/hiv_insight
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