Book notes for "Expecting Better", Why the Conventional Pregnancy Wisdom is Wrong and What You Really Need to Know
A very interesting book, it is reassuring to know the actual source
behind many recommendations during pregnancy, and a reminder that in
many cases it can be important to check for yourself if conventional
wisdom applies to your own situation and values, or if conventional
wisdom is even based in fact. Often with medical matters we tend to rely
entirely on our doctor, but having more knowledge (as long as it is
based in fact) can only empower us to make better decisions.
After this book I moved on to some post-pregnancy books. Unfortunately
there are none by this author at the moment.
Insights, lessons learnt:
It is worth spending time to research things, and look at the data
directly, since often people make descisions for you (see: cosleeping,
alcohol in pregnancy) because they believe the outcomes for that
recommendation to be better at a population level. If you make decisions
for yourself, you can optimise.
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The main research on this uses data from the 19th century (it's old,
but the technology hasn't changed much!). Here is the idea: prior to
the modern era, couples would pretty much get down to business right
after the wedding and there were limited birth control options. So
you can figure out how fertility varies with age by looking at the
chance of having children at all for women getting married at
different ages. Researchers found that the chance of having any
children was very similar for women who got married at any age
between 20 and 35. Then it began to decline: women who got married
between 35 and 39 were about 90 percent as likely to have a child as
those who got married younger than 35; women who got married between
40 and 44 were only about 62 percent as likely; and women who got
married between 45 and 49 were only 14 percent as likely.
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Obese women have more pregnancy complications, as the graph on the
next page illustrates. One example: 23 percent of normal-weight
women have a C-section, versus almost 40 percent of obese women. The
risk of pre-eclampsia, a serious pregnancy complication, is more
than three times as high if you are obese.
> Drinking cannot harm baby in first 2 weeks!
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For the period between fertilisation (around ovulation or a day or
two later) and your missed period, your baby is a mass of identical
cells. Any of these cells could develop into any part of the baby.
If you do something that kills one of these cells (such as heavy
drinking or some kind of really bad prescription drug use), another
cell can replace it and do exactly the same thing. The resulting
baby is unaffected. However, if you kill too many of these cells,
the embryo will fail to develop and you will not wind up pregnant at
all. It's an all-or-nothing thing.
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In the 1920s, doctors identified a hormone, hCG, that is secreted in
the urine of pregnant women. A test was developed based on this, but
it wasn't very user-friendly. It required injecting the urine into
the ear of a live rabbit that was subsequently killed and dissected.
It wasn't until the 1960s that doctors figured out how to test for
this hormone without the rabbit.
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Some researchers suggest that as many as 50 percent or more of
fertilised eggs do not result in pregnancy; of course, not all of
these fertilisations are detected even with very sensitive tests.
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If you are seen at six weeks and things look normal, what is the
overall chance that you will have a miscarriage? The data suggests
about 11 percent. If you are seen later, say, at eight weeks and
things look normal at that point, then the chance of miscarriage is
lower, about 6 percent. By the eleventh week, it has dropped to less
than 2 percent.
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A study in England showed that the chance of first-trimester
miscarriage was around 4 to 5 percent for first pregnancies or women
with a previous successful pregnancy. But for those with a previous
miscarriage, it was around 25 percent.
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A second factor is age. Older women are more likely to miscarry
(this is likely related to a higher rate of chromosomal problems).
These effects are large. In one study the miscarriage rate was 4.4
percent for women under 20, 6.7 percent for women 20 to 35 and
almost 19 percent for women over 35.
- Highlight Loc. 1534 | Added on Sunday, March 06, 2016, 08:45 AM
Averaging across a few studies, researchers found that a 1
microgram/gram increase in mercury level led to a decrease of 0.7 IQ
- Highlight Loc. 1547-48 | Added on Sunday, March 06, 2016, 08:46 AM
increasing your DHA intake by 1 gram per day would increase your
child's IQ by, on average, 1.3 points.
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The fish in the top right quadrant are the best: these are fish that
are high in omega-3s but low in mercury, such as herring and
sardines (small, oily fish) and salmon. Eating more of these fish
can be nothing but good. Eighty-five grams of sardines a day would
have a huge impact on your omega-3 intake, but virtually no effect
on mercury level. Other fish - those on the bottom left - are
obviously bad. Take something like orange roughy (not a super common
choice, but not totally unknown): not a lot of omega-3s and a whole
load of mercury. Sadly, my favourite choice of tinned tuna is in
this area, as well. And then there are those in the middle. The fish
on the bottom right - tilefish, swordfish, sushi-grade tuna - are
ambiguous. Although they are high in mercury, they also have a lot
of omega-3s. You make your kid a little less smart with the mercury
and a little smarter with the omega-3s. They're obviously not as
good as the herring and sardines, but they're a lot better than the
grouper and the orange roughy. Faced with a choice between tinned
tuna and sushi tuna, the sushi-grade tuna is, surprisingly, probably
a better choice. It's a little higher in mercury, but a lot higher
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Almost 90 percent of women report some symptoms of nausea and more
than half report some vomiting as well. This tends to peak at around
eight or nine weeks of pregnancy and fall off after that. The graph
below gives you a sense of how many women report being sick by week
of pregnancy. 2 Almost 50 percent of the women in this study
reported vomiting at some point in weeks five to eight of pregnancy,
but it was less than 15 to 20 percent by seventeen weeks.
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The average pregnant woman starts to feel bad at around six weeks
(that's two weeks after her missed period). She starts feeling
better at around thirteen or fourteen weeks, a couple of weeks into
the second trimester. During this time, she may or may not throw up
at all. If she does, it will typically be concentrated in just a few
days (although those days might be quite bad). If you are throwing
up every day for a month, that is unusual: in these studies, only
about 5 percent of women report nausea that severe.
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one study showed that the overall risk of first-trimester
miscarriage was 30 percent for women without nausea versus just 8
percent for those who were nauseated.
- Highlight Loc. 1877-81 | Added on Sunday, March 06, 2016, 10:04 AM a
study in England of about 57,000 pregnancies. This study found that
the first trimester screening could detect 91 percent of Down's
syndrome cases. This study also answered my second question. The
researchers reported a 6.3 percent false positive rate. This means
that for every 100 women tested, about 6 of them were told they were
positive but in fact their babies turned out to be perfectly
- Highlight Loc. 1930-31 | Added on Sunday, March 06, 2016, 10:07 AM I
was 31. My initial risk was about 1 in 700. If I did this screening,
about 89 percent of Down's syndrome cases would be detected. Taking
into account the few false positives, my final risk would go down by
about almost a factor of 10, to about 1 in 6,000.
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The authors collected data from 500 women, about half of whom had a
girl and half a boy. The average female heart rate was 151.7, and
the average male heart rate was 154.9. These were not significantly
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Women who do Kegels regularly are significantly less likely to have
urinary leakage. Of course, this is just like any other exercise: it
works by building up your muscles. So there is no reason not to
start even before you are pregnant, although these studies show you
can get the benefits of the exercise even if you start midway
through the pregnancy.
- Highlight Loc. 2641-43 | Added on Sunday, March 06, 2016, 01:58 PM A
review article from 2009 suggests that women who are encouraged to
do these exercises are less than half as likely as control women to
experience any urinary incontinence during late pregnancy or in the
post-natal period. This is especially true for women having their
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Most evidence suggests that restrictions on back sleeping are
overblown, although one recent study disagrees. Concrete guidance is
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Although there are no randomised trials in pregnant women, the
evidence on the safety of paracetamol is vast, which is why it
deserves the Category B ranking.
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There is a bit of randomised controlled trial evidence on this. In a
study of 1,200 women with singleton pregnancies and threatened
pre-term labour, about 400 of them were put on bed rest and the
other 800 were not. Bed rest was not effective at preventing
pre-term birth (7.9 percent of the bed rest group and 8.5 percent of
the control group had their babies prematurely). 7 There's more
randomised evidence for multiple gestations and again, there is no
evidence that women put on bed rest had fewer pre-term deliveries or
better general outcomes.
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You are most likely to have your baby in your 39th week of
pregnancy: close to 30 percent of babies are born in this week. The
next most common week is week 38 (18 percent), followed by the 40th
week (17 percent). About 70 percent of babies are born before their
due date. This includes all births; first births and those that are
not induced tend to be a bit later.
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If you get to your due date without a baby, there is a 60 percent
chance you'll have the baby in the next seven days. If you haven't
had the baby by 41 weeks, there is about a 60 percent chance you'll
go into labour spontaneously. At 42 weeks the vast majority of
doctors will induce labour.
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AM The most precise data I could find on this comes from one study
in the United Kingdom that measured this effacement by ultrasound at
37 weeks and then recorded the chance of going into labour by the
due date. The graph below shows the results. For women who were more
than 60 percent effaced (that means shortened about halfway) at 37
weeks, almost all of them (something like 98 percent) went into
labour before their due date. On the other hand, for women who were
less than 40 percent effaced, almost none of them (less than 10
percent) went into labour before their due date.
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researchers find that women who are induced with Syntocinon are more
likely to use an epidural; increased use of pain relief probably
points to increased pain (at least before the epidural was
administered!). Secondly, there is both direct and indirect evidence
that induction can increase the risk of a C-section. This seems to
be most true when Syntocinon is used alone. Of course, C-sections
are safe and common, but recovery from them still tends to be harder
than recovery from a vaginal delivery.
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Caesareans are generally safe and they are common (about 25 percent
of births in the United Kingdom). But obstetricians generally agree,
for good reason, that they are not the preferred mode of delivery. A
Caesarean is major abdominal surgery. Recovery varies across women,
but is generally slower than after a vaginal delivery.
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But large randomised studies have shown that vaginal delivery of
breech babies is slightly riskier than a planned Caesarean.
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PM The epidural is extremely popular: it was used in about
two-thirds of births in the United States in 2008 and in the UK,
about 30 percent of women have an epidural.
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Primary conclusion: from the standpoint of the baby, the epidural
mostly doesn't matter. Babies who are born to mums who have an
epidural are no more likely to spend time in the NICU and no more
likely to have low APGAR scores (meaning they are not more likely to
be "lethargic", which is one concern that is bandied about).
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Negative impacts: Greater use of instruments (forceps or vacuum in
delivery), greater use of Caesarean for foetal distress, longer
pushing time (15 minutes), higher chance of baby facing up at birth,
greater use of Syntocinon in labour, greater chance of low maternal
blood pressure, less able to walk after labour, greater chance of
needing a catheter, increased chance of fever during labour No
differences: Overall Caesarean rate, length of dilation period of
labour, vomiting during labour, long-term backache
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An older study, published in 1991, showed similar impacts. Women in
this study were randomly assigned to have either a supportive doula
or an observer in the room who did not help. Women with a doula were
less than half as likely to have an epidural, had shorter labour,
were about half as likely to have a Caesarean and were half as
likely to have forceps used in delivery.
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Based on this evidence, both this review and the most commonly used
obstetrics textbook suggest that continuous monitoring isn't
necessary or even a very good idea for most women. It seems like
what is happening is that doctors overreact to patterns they see in
the heart rate when the baby is not actually in distress. It's
almost as if there is too much information. You might imagine that
every baby, no matter how well the birth is going, has a few moments
when her heart rate dips.
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Syntocinon after birth: Useful in preventing postnatal haemorrhage.