26 September 2020 | New Scientist | 13FERTILITY-TRACKING apps can
provide misleading information
and shouldn’t be relied on to
help people conceive or as a
contraceptive tool, according to
an analysis of mobile phone apps
available in the UK and Canada.
There are hundreds of apps
that offer to track periods in order
to help people either achieve or
avoid pregnancy. To find out how
reliable they are, Joyce Harper at
University College London and her
colleagues considered all 200 of
the fertility-tracking apps offered
on Apple’s mobile iOS app store.
The team removed apps from
the list if they were faulty, hadn’t
been updated within three years
or didn’t offer to predict a user’s
“fertile window”. This left 90 apps.
Just over half of those predicted
this window based on when
a user has their period.
This “calendar method” is based
on the idea that ovulation typically
happens on day 14 of the menstrual
cycle and fertility is highest in the
days before this. But this method
is flawed, says Harper. “Not every
woman has a 28-day cycle, we
don’t all ovulate on day 14,” she
says. Harper’s recent research,
based on the data from another
fertility app, suggests ovulation
occurs on day 17, on average.
“In our study, women ovulated
anywhere between day 10 and day
26,” says Harper. Apps that rely
only on dates provide inaccurate
information, and could, say,
result in some users missing their
fertile window, she warns.The more robust apps took
into account other markers
of fertility based on user input,
such as body temperature, which
rises during ovulation, and
information about the changing
state of cervical mucus. Harper
says she was surprised to find that,
on the whole, the free apps used
more of these biomarkers than
paid-for apps did (Reproductive
BioMedicine Online, doi.org/d9bj).Still, no prediction will be
perfect, and only 57 per cent of
apps provided any disclaimer to
this effect. Just five advised against
using the app to avoid getting
pregnant. “They shouldn’t be
relied on for contraception,”
says Rhonda Zwingerman at the
University of Toronto in Canada,
who wasn’t involved in the study.
That doesn’t mean apps can’t
be useful. Apps that track period
dates can help those who want to
be reminded when their period is
due, or could indicate if periods
seem unusually far apart, which
might signal ovulation problems.
Yet they aren’t always accurate.
In other research, Harper has
entered the same dates into
10 apps, and they gave varying
dates of the next period. And
Zwingerman has shown that
about 22 per cent of such apps
had “serious inaccuracies” in
information they provided.
“Almost all of those claimed to
be able to predict the gender of
your child based on when you
had intercourse in the cycle,”
says Zwingerman. “Just to be
clear, that’s not how it works.” ❚Technology
Jessica Hamzelou
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MAGES/I
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HOTOMany fertility-tracking
apps give imprecise
ovulation predictionsHealth
Nut allergies spike
on Easter and
Halloween
EACH year, severe allergic reactions
to nuts spike in children around
Easter and Halloween, according to
an analysis of data from emergency
rooms across Canada.
“I’m not so surprised,” says
Moshe Ben-Shoshan at McGill
University in Montreal, who led
the study. As a paediatric allergist
who regularly works in the
emergency room, he noticed that
severe allergic reactions among
children tended to go up at certain
times of the year.
Ben-Shoshan and his colleagues
used records of emergency room
visits to analyse the incidences of
nut-induced anaphylaxis – a severe
allergic reaction – in children across
Quebec, Ontario, British Columbia
and Newfoundland and Labrador.
In 1390 cases between 2011
and 2020, they saw that rates of
peanut-triggered anaphylaxis were
85 per cent higher than average
on Halloween and 60 per cent
higher during Easter. They saw
a similar trend for anaphylaxis in
cases where it wasn’t clear if thechild had eaten tree nuts or peanuts
(Canadian Medical Association
Journal, doi.org/d9mg). The team
didn’t find a significant increase
in nut-induced allergic reactions
during other holidays, such as
Christmas, Diwali, Chinese New
Year and Eid al-Adha.“Halloween and Easter
involve social gatherings with
other children in the presence of
a lot of candy. These holidays may
include interactions with other
adults who may not be aware
of the child’s food allergies,” says
Tina Sindher at Stanford University
in California. She adds that “a lot
of fun-size candy may not be
labelled appropriately”.
Children with food allergies
should always carry an epinephrine
autoinjector, such as an EpiPen, and
parents should make other adults
aware of allergies, says Sindher. ❚
Layal LiverpoolHalloween treats
can trigger
dangerous
reactions in
children with
nut allergiesSHUT
TE
RSTO
CK/ASFOODSTUDIOMost fertility apps are unreliable,
but free ones work best
22%
Proportion of period-predicting
apps with “serious inaccuracies”