Differences in the growth, weight, and body fat levels of
children conceived through fertility treatment are small,
and no longer apparent by late adolescence, finds new
research.
The University of Bristol-led study,
published in the American Medical Association’s open
access medical journal JAMA Network, is the first to
look at whether fertility treatment is associated with
differences in growth, weight, and body fat from infancy to
early adulthood.
The study included information
collected by Growing Up in New Zealand, this
country’s largest longitudinal study of child development
which is following the lives of more than 6000 children from
before they were born through until
adulthood.
Since the first birth of a child by
in vitro fertilisation (IVF), questions have been raised
about the risks to children conceived this way. While
previous studies have shown an increased risk of low
birthweight and preterm birth in offspring conceived by
assisted reproductive technology (ART), relatively little is
known about long-term growth and weight gain.
The
study, led by an international research group from the
Assisted Reproductive Technology and Future Health
(ART-Health) Cohort Collaboration, assessed whether
conception by ART, which mostly involves IVF, was associated
with differences in growth, weight, and body fat from
infancy to early adulthood.
The study drew on data
from 158,000 European, Asian-Pacific, and Canadian children
conceived by ART including more than 6000 New Zealand
children.
The team’s findings show those conceived
using ART were on average shorter, lighter, and thinner from
infancy up to early adolescence compared with their
naturally conceived peers. However, the differences were
small across all ages and reduced with older age.
Dr
Ahmed Elhakeem, Senior Research Associate in Epidemiology at
the University of Bristol, and lead study author, said
“this is important work. Over the last three decades
conception by ART has increased. In the UK just over one in
30 children have been conceived by ART, so we would expect
on average one child in each primary school class to have
been conceived this way. Since the first birth of a child by
IVF, concerns have been raised about the risks to the
children conceived.
“Parents and their children
conceived by ART can be reassured that this might mean they
are a little bit smaller and lighter from infancy to
adolescence, but these differences are unlikely to have any
health implications. We acknowledge it is important that as
more people conceived by ART become adults, we continue to
explore any potential health risks at older
age.”
Dr Caroline Walker, a Senior Research Fellow
at the University of Auckland, and a member of the
Growing Up in New Zealand team who collaborated on
the ART study says New Zealand has similar rates of
infertility to the UK.
“In 2019 New Zealand
fertility clinics reported nearly 8000 cycles of ART
resulting in 1769 babies being born. This equates to
approximately three percent of births in any given
year”.
Dr Walker also noted the value in having New
Zealand data included in the study.
“Because
Growing Up in New Zealand is following the lives of a
large cohort from before they were born through to
adulthood, we are able understand specifically how things
like ART impact New Zealand children over a long period of
time. There are tens of thousands of children in New Zealand
born as a result of fertility treatment and studies like
this enable us to speak more confidently about outcomes for
these children in a local context”
The researchers
say studies with larger samples at older ages are now
needed. Other outcomes such as cardiometabolic risk factors
following ART also require investigation. The collaboration
network, developed as part of the study, will facilitate
future research into health outcomes following
ART.
The study, funded by the European Research
Council under the European Union’s Horizon 2020 research
and innovation program, Medical Research Council (MRC),
British Heart Foundation (BHF) and National Institute for
Health and Care Research Bristol Biomedical Research
Centre.
Paper
Read the full paper
here. or here ‘Association
of assisted reproductive technology with offspring growth
and adiposity from infancy to early adulthood’ by Ahmed
Elhakeem, PhD et al. in JAMA Network
Open
Notes:
A
total of 26 longitudinal cohort studies with participants
from Europe (20 cohorts), Australia (2 cohorts), New Zealand
(1 cohort), China (1 cohort), Singapore (1 cohort) and
Canada (1 cohort) were included in this
study.
About Growing Up in New Zealand’s
involvement in this study:
Growing Up in New
Zealand (GUiNZ) GUiNZ is a prospective birth cohort
study that recruited 6,853 children via their pregnant
mothers if they had an expected delivery date between 25
April 2009 and 25 March 2010 and were residing within a
geographically defined region of New Zealand which was
chosen because it could provide a cohort of births that
would be representative of all current births in NZ,
especially with respect to ethnic and socioeconomic
diversity. Birth parameters were retrieved via linkage to
routine perinatal records (with maternal consent) and
repeated child height and weight measurements were collected
as part of field interviews when the children were 2, 4 and
8 years of age and waist measurements at 4 and 8 years of
age.
Anthropometric measurements were undertaken by
trained interviewers using a standardised approach used by
the NZ Ministry of Health. Up to 173 ART-conceived offspring
and 4,274 NC offspring were included in this study. GUiNZ
contributed results to the main analysis (ART vs. NC) to
additional analysis stratified by sex, for height, weight,
BMI, and waist circumference. Data were available for all
study confounders (maternal age, BMI, smoking, education,
ethnicity, parity and offspring sex and age at outcome
assessment).
Growing Up in
New Zealand is a University of Auckland
study, managed by UniServices Limited and is funded by the
New Zealand
Government.
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