University College London(June 21, 2023)
Around 20% of women who needed fertility treatment, such as IVF, to conceive their first child
are likely to get pregnant naturally in the future, finds a new UCL study.
The first-of-its-kind research, published in Human Reproduction, analysed data from 11 studies
of over 5,000 women around the world between 1980 and 2021, to evaluate how common it is
to get pregnant naturally after having a baby conceived by fertility treatment.
They found that at least one in five women conceived naturally after having had a baby using
fertility treatment such as IVF mostly within 3 years. This figure remained unchanged, even
when taking into account the different types and outcome of fertility treatment — alongside
length of follow up.
Infertility is defined by the failure to achieve a pregnancy after 12 months or more of regular
unprotected sexual intercourse, and it is estimated to affect 1 in 7 heterosexual couples.
However, not all women seeking and undergoing fertility treatment are absolutely or
permanently infertile. And half of couples who struggle to conceive naturally in the first year
of trying will go on to do so in the second year.
Although it is typically considered ‘rare’ for a woman to get pregnant naturally, if she has
previously had fertility treatment, the researchers want to highlight how it is not in fact an
unusual event.
The team consider the findings to be particularly important, as many women may not realise
that they could conceive naturally following fertility treatment.
This could lead to them becoming pregnant again quickly or when they aren’t ready — which
could be problematic for both the health of the mother and child.
Lead author, Dr Annette Thwaites (UCL EGA Institute for Women’s Health) said: “Our
findings suggest that natural pregnancy after having a baby by IVF is far from rare. This is in
contrast with widely held views — by women and health professionals — and those commonly
expressed in the media, that it is a highly unlikely event.”
Much has changed since the early days of IVF and it is now used for a wide range of causes of
infertility, including cases where no cause is ever found.
In addition, some women may not have experienced infertility at all but used treatment for
other reasons. This could include single women using donor sperm, women in same sex
relationships, surrogates or those seeking to screen for serious genetic conditions.
So, it is important for those who have had successful IVF to know how likely they are to
conceive naturally afterwards.
IVF was first used in 1978 and now, more than 10 million babies worldwide have been born
using the treatment — equating to between 1% and 6% of all babies born per year in the
developed world by 2020.
In order to track the data more accurately and analyse which factors make natural pregnancy
after having a baby by fertility treatment more likely, the researchers are calling for linked
national data sets.
They hope that this information could then be used to counsel people considering their options
after successful fertility treatment.
Dr Thwaites said: “Knowing what is possible would empower women to plan their families
and make informed choices regarding further fertility treatment and/or contraception.”
Study limitations
The included studies were mostly of moderate quality and varied widely by geography, cause
of subfertility, type and outcome of fertility treatment and length of follow up making direct
comparisons difficult.