"Caution: Anti-inflammatory Foods in the Third Trimester"
The right side of the heart, shown here in blue,
pumps deoxygenated blood from the body to the lungs,
where it can fill up with oxygen,
and then the left side of the heart,
shown here in red pumps oxygen rich blood
from the lungs to the rest of the body.
So blood travels from the body, to the right side of the heart
to the lungs to the left side of the heart, back to the body.
But what if you’re still in the womb?
When you’re a fetus your lungs don’t work,
because they’re filled with fluid.
So how does your heart bypass the lungs and spread
the oxygen-rich blood coming in through
the umbilical cord to the rest of your body?
Before we’re born we have an extra blood vessel
called the ductus arteriosus that directly connects
the right side of the heart with the left side of the heart,
bypassing the fluid filled lungs— until you’re born,
and you take your first breath and then this blood vessel closes.
But in about 1 in 10,000 births this blood vessel closes prematurely
while the baby’s still inside, necessitating an emergency C-section.
Most cases for which there’s a known cause
are thought to be related to taking anti-inflammatory drugs
like aspirin or ibuprofen.
This is because the way your body keeps this blood vessel open
is with a class of inflammatory compounds called prostaglandins.
If you take an anti-inflammatory drug you can underlmine
your body’s ability to keep it open and it could constrict closed prematurely.
That’s why most authorities recommend that these NSAID anti-inflammatory drugs
be avoided in the third trimester.
The likelihood anything bad is going to happen is extremely remote,
but better safe than sorry.
Sometimes this premature constriction happens
even when women are NOT taking drugs, though,
so called “idiopathic” cases, which is doctorspeak for
“we have no idea what causes it”.
If anti-inflammatory drugs can cause it, though,
what about anti-inflammatory foods?
A few years ago I profiled two cases apparently caused by pregnant women
drinking chamomile tea,
one of which reversed. The ductus opened right back up
once the tea was stopped,
but the other baby had to come right out.
Since then, there have been other case reports,
for example a women who had been drinking
a few ounces of an acai berry drink every day
or another woman who was drinking prune juice,
and a violet vegetable juice containing a blend of fruits and veggies.
Pregnant women should therefore take special care when consuming
lots of these powerful anti-inflammatory berry nutrients.
What about berries themselves, and green tea,
and all the other wonderful anti-inflammatory foods and beverages out there?
This group of researchers in Brazil compared ultrasounds
of third trimester babies’ hearts inside moms who ate a lot of
these anti-inflammatory foods compared to women who ate less
and they could tell a difference.
The speed of blood through the ductus in the anti-inflammatory diet moms
was higher, suggesting it was narrower,
just like when you pinch the opening of a hose closed
and can make water shoot out faster.
And also the right sides of the hearts of the babies
in the anti-inflammatory diet moms were larger than their left sides
suggesting some blood back-up,
again an indicator of a tighter ductus.
The researchers suggested changes in late pregnancy diets may be warranted,
but critics replied that the differences they noted may not
have any clinical relevance, meaning it may not matter if the vessel
is a little more open or closed.
And look, we don’t want to freak women out as many of these
anti-inflammatory foods may be beneficial like cranberries
for example, which may be useful in preventing urinary tract infections
that can be a risk factor for premature birth.
So cranberries are attractive from a public health
and cost consideration standpoint
if it can prevent some of these premies from being born too early.
So before cutting down on a healthy food like cranberries
we want some stronger evidence that they’re potentially harmful.
What about confounding factors, for example—
maybe women who ate lots of anti-inflammatory foods
had other characteristics that could affect fetal blood flow.
What we need is an interventional trial where you take pregnant women,
change their diets and see what happens,
but we didn’t have such studies…
until now.
And a few weeks during third trimester cutting back on anti-inflammatory foods
like tea, coffee, dark chocolate, grapes, and citrus
did indeed seem to open the ductus.
This was just during normal pregnancies.
In women whose fetuses had abnormally constricted vessels,
a few weeks on removing polyphenol rich foods
reversed the ductal constriction in 96% of cases.
Now importantly they didn’t follow these babies after birth
to see if it made any difference.
That complete closure only happens in 1 in 10,000 births;
we’re not sure what effects just relative levels of constriction
may have so it’s too early to be instituting a ban
on dark chocolate for pregnant women.
At this stage we’re left with is just a note of caution.
So during the rest of your life I recommend piling these healthy foods
like berries and cocoa powder,
but from about 28 weeks until birth
pregnant women may want cut back until we know more.