Women with asthma could take longer to
conceive, according to new research. The study, published online in the
European Respiratory Journal, adds new evidence to suggest that asthma has a
negative effect on fertility.
Researchers from Bispebjerg University
Hospital in Denmark analysed data from questionnaires completed by a cohort of
over 15 000 twins living in Denmark aged up to 41 years.
Representative of whole population
The questionnaires included questions on
the presence of asthma and on fertility. Twins were used in this research, as
they not only enable direct comparisons to be made between twin sisters, but
also comprise a sample representative of the whole population, being born into
all social groups and avoiding the need to measure genetic and lifestyle
information for each individual.
The researchers divided the participants
into women with asthma and those without, and then sub-divided the groups into
those treated for asthma and those not treated for asthma. All participants
were asked whether they had been trying to get pregnant for longer than a year
without success and how many children they had given birth to.
955 of the participants reported a history
of asthma. The results found a significantly higher proportion of women who
experienced a prolonged time to pregnancy in the group with asthma, compared to
those who did not have asthma (27% of asthmatics vs. 21.6% of non-asthmatics).
The risk of a delay in conceiving
significantly increased in women with untreated asthma compared to those with
asthma who were undergoing treatment (30.5% of untreated asthma group vs. 23.8%
of those receiving treatment).
The researchers also noticed an interesting
trend in the age of participants. Women above the age of 30 with asthma had an
even stronger tendency towards a long waiting time to pregnancy (32.2% women
above the age of 30 vs. 24.9% of women under the age of 30). However, the
overall results of the study showed that women with asthma ultimately gave
birth to the same average number of children as women without asthma, as those
with asthma tended to have children earlier in life than those without asthma.
Lead author, Dr Elisabeth Juul Gade, said:
"Our results shed light on the complex interactions between fertility and
asthma. Although we observed women with asthma experiencing longer waiting
times to pregnancy, our findings suggest that if women take their medication
and control their asthma, they can reduce this delay.
"As the negative effect of asthma on
fertility is reduced by treatment, we can assume that the systemic inflammation
characterised by asthma may account for the effect on delaying fertility.
"Despite the delay, our overall
results suggest that women with asthma had the same number of children, which
is due to the fact that they tend to conceive at an earlier age compared to
those without, getting a head start on their reproductive life."