Tag Archives: pregnancy

Giving birth after a caesarian delivery

We are due our second child in February next year (a 20-month gap between no.1 and no.2 – yes, I’m weary just thinking about it). I shall spare you the warts-and-all birth story, but our first baby was born by caesarian section after a worrying dip in his heart rate.

There are two options for women in this situation. The first is to choose to have a caesarian delivery again, which is known as “elective repeat caesarian delivery”, or ERCD for short. The second is to have a “vaginal birth after caesarian”, often abbreviated to VBAC. The actual process of attempting a VBAC is called “trial of labour after caesarian”, or TOLAC.

If we were living forty years ago, there wouldn’t be much debate – we would have been booked in for a C-section. This started to change in the 1980s as more women and couples pushed to have a more ‘natural’* vaginal birth, which led to an increasing number of VBACs. This was backed by improving caesarian surgery, such as a change from making the incision ‘up’ the belly (‘longitudinal’) to making it ‘across’ the belly (‘transverse’) to achieve more effective repair, as well as advice from leading health organisations to reduce caesarian rates.

It seems that in the UK, however, as in many other countries, caesarian deliveries after previous caesarians are back on the increase. One reason is the real fear that the uterus, weakened by the surgery, even by a transverse section, might rupture if a vaginal birth is attempted. A ruptured uterus can lead to complications for the mother and child (more on the specifics in a minute).

There are currently no randomised trials to compare the risks associated with two approaches and most studies have looked retrospectively at what happens in ERCDs or VBACs. This means that it’s hard to inform women before they give birth what the different risks might be.

An article in the scientific journal PLOS Medicine earlier this year – ‘To VBAC or Not to VBAC‘ by Catherine Spong – summarised two research papers that were published at the same time. They both capture information on what the mother intended to do, as well as what actually happened. This gives some relevant insight into whether preferences were successfully carried out, and what the true risks are for women planning either an ERCD or VBAC.

And good news, there’s no paywall so access is free!

The headline message for the woman is:

…risks such as uterine rupture are higher for women attempting a trial of labor following a previous cesarean delivery than those having an elective repeat cesarean delivery; however, the overall risks are low in both groups.

So how does it break down?

The mother

One study was based in the UK and the other in Australia, and both calculated that the uterus ruptures in approximately 2 in 1,000 planned VBAC cases and 1 in 1,000 planned ERCD cases. These figures are lower than those previously reported and communicated to patients, which range from 4-12 ruptures in every 1,000 women planning VBACs. The authors of the Australian study put this down to the hospitals following standardised treatment plans that were designed using the latest evidence. Either way, the results are encouraging.

The British study also found that the risk of rupture is higher for women who have had two or more previous caesarean deliveries, less than 12 months since their last caesarean section, or whose labour was induced (up to roughly 6 in every 1,000 cases, if I’ve calculated correctly, so still relatively low).

As for how the intended modes of delivery played out, nearly 98% of women who planned an ERCD succeeded, but only 57% of those who planned a VBAC did. Almost 25% of women originally planning a VBAC ended up choosing a caesarian delivery, which suggests they either changed their minds or doctors advised that a caesarian should be carried out instead.

The baby

The Australian study also assessed the outcomes for the babies. The researchers recorded fewer serious problems for the babies in the ERCD group when compared with the babies in the VBAC group – approximately 1 in a 100 ERCD births had difficulties, whereas over 2 in a 100 VBAC births had problems for the baby. Serious problems that needed treatment included physical birth injuries, infection and low oxygen in the umbilical cord.

There were two stillbirths in the VBAC group, but as Catherine Spong explains in the summary piece, there’s an important caveat to note. Elective caesarians, by their nature of being chosen, happen at a set time – in the Australian study the C-sections were performed, on average, after 38.8 weeks of term. Laboured vaginal births, by their nature of being involuntary, cannot be booked in, and the average time that these took place was at 40 weeks of term. As a result, it is uncertain whether these stillbirths were associated with the type of delivery or the extra time in the womb (or, even, that they happened by chance – 2 is a very low number from which to draw conclusions).

The state of play

Uterine rupture can increase the risk of stillbirth. According to statistics cited in Spong’s article from the National Institutes of Health in the US, infant death occurs in 6% of cases of a ruptured uterus – given the rates of rupture reported by these two studies, it puts the estimated risk somewhere in the region of 3 deaths every 50,000 ERCDs and 6 deaths every 50,000 VBACs.

Uterine rupture can also increase the risk of brain damage to the baby due to a lack of oxygen (‘hypoxic-ischaemic encephalopathy’, or HIE). Another review estimated this risk to be one in every 1,250 VBACs against practically zero risk in ERCDs.

However, these ever-so-slightly higher risks of complications in VBACs need to balanced against other potential problems associated with caesarian deliveries. Serious infant respiratory problems are more common in elective caesarians (observed to be 3-6 in 400) compared with vaginal deliveries (observed to be 1 in 400). Newborns are also more likely to be admitted to the neonatal intensive care unit (NICU) due to the need for ventilation therapy and more likely to spend longer than seven days in hospital. Other caesarian-specific risks to the mother, such as dislodged blood clots, need for a blood transfusion, extended wound healing, a longer stay in hospital and future pregnancy complications, are also present.

The extent of some of these risks is greatest in the cases of caesarian sections following failed VBACs, which means understanding which women are most likely to have a successful VBAC is hugely important. A group of US clinicians highlighted various factors that increase the likelihood of a successful VBAC: women with one previous caesarian delivery with a low transverse incision, women who at some point have had a prior successful vaginal delivery, and women who had their caesarian because the baby presented breech or some other form of malpresentation rather than for other reasons. Vaginal births in general are more successful when women have access to high level of healthcare, something we should always seek to protect and improve wherever necessary.

Other factors decrease the likelihood of a successful VBAC: failure of the labour to progress or baby to descend during a previous TOLAC, a higher age and weight of the mother, and preexisting medical conditions such as hypertension or diabetes.

And, so…?

What does all this population data mean for the individual woman? The risks for TOLAC seem reasonable in the context of the inherently uncertain process of labour, but women should be properly prepared and counselled to understand the benefits and risks. This should ideally be done with full reference to real numbers and so that the discussion takes the individual’s status into account. That way, the chances of a satisfactory outcome for mother, child and doctor can be at its greatest.


*I hesitate to use natural to describe vaginal births: ‘natural’ has so many connotations about medical interventions and vaginal births vary from case to case, which renders ‘natural’ a bit of a messy description.

What not to do during pregnancy and childbirth

Ben Goldacre – author of Bad Science, scourge of secretive Pharma companies, and champion of evidence-based healthcare – highlighted a great resource on his secondary blog. It is a collection of ‘do not do’ recommendations from the National Institute for Health and Clinical Excellence (pleasingly abbreviated to NICE), which publishes guidelines on best healthcare practices within the UK’s National Health Service.

The ‘do not do’ database holds information on a range of clinical practices that NICE recommend should be stopped or not used routinely, all of which is based on the best available evidence. There is a section on ‘Gynaecology, Pregnancy and Birth’, which contains 174 recommendations. Many are for specific interventions that may be more of interest to health professionals, such as “A serum ferritin test should not routinely be carried out on women with heavy menstrual bleeding (HMB)”. But there are a few nuggets that mothers- and fathers-to-be may like to hear.

There is a range of advice on alternative and complementary therapies, for instance: “Healthcare professionals should inform women that the available evidence does not support herbal supplements, acupuncture, homeopathy, castor oil, for induction of labour”. There is no evidence for hot baths, enemas or sexual intercourse either. For labour pain, transcutaneous electrical nerve stimulation (TENS) should not be offered to women in established labour”, which our midwife obviously had not read (or just ignored!).

As for acupuncture, acupressure and hypnosis, they “should not be provided, but women who wish to use these techniques should not be prevented from doing so”, which seems sensible, although potential side effects should be forgotten. Generally for alt med, it advises that: “Pregnant women should be informed that few complementary therapies have been established as being safe and effective during pregnancy. Women should not assume that such therapies are safe and they should be used as little as possible during pregnancy.” Sound  advice.

There is a mention of supplements during pregnancy – iron supplements shouldn’t be taken routinely (unless a deficiency is identified) – but I would love to see that section expanded to cover other areas of nutrition. More specifically, there is no good evidence that magnesiumfolic acidantioxidants (vitamins C and E), garlicfish oils or algal oils can help prevent disorders related to high blood pressure, such as pre-eclampsia.

A random titbit that’s not really connected with other recommendations, says that if a women wants to breastfeed, then breast examination during pregnancy does not seem to help breastfeeding in the long run.

There are more pieces of intriguing guidance about midwife support during labour (“Team midwifery and active management of labour), psychosocial interventions to reduce the likelihood of developing a mental disorder, and approaches to fertility problems.

All of which can only be good for mums and dads in making informed decisions and for health professionals in providing the best care possible. Happy browsing!

The influence of early eating habits in children

Our little one, who is now 10 months old, seems to have got his eating sorted after a stubborn start. We started weaning around the World Health Organization’s recommended 6-month mark, using a mix of spoon feeding and baby-led weaning (more on that in later post). Since then, it has seemed apparent that some things have gone down better than others: scrambled eggs, yoghurt, cheese, toast, chicken, bananas and strawberries were all early hits, while broccoli, tomatoes and beef were swiftly rejected.

He seems to have developed an appetite for some foods after a unsure start, such as cucumber, carrot and apple. And this brought to mind a Naked Scientists podcast from a few months ago, which featured an interview with Marion Hetherington, Professor of Biopsychology at the University of Leeds, on children’s appetite and eating behaviour.

The full transcript is available here and the audio is available here. I’ve made a few summary points below, but do check out the full interview.

  • A developing foetus can encounter tastes and odours derived from the mother’s diet and toxins from the environment, and this may affect later food preference.
  • Babies fed with breast milk are exposed to a greater variety of flavours than are formula-fed babies, and this can mean they are more willing to try new tastes.
  • Babies are primed to accept sweet tastes from birth, whereas bitter tastes are rejected. This means that we have to learn to like bitter foods but not sugary foods.
  • Parents may need to try their baby 8-10 times with a new flavour before the child will accept it, so parents shouldn’t give up after the usual 2-3 times. Also, there may be a sensitive period between 6-9 months in which to introduce new flavours and textures, after which it becomes harder for the child to accept a new food.
  • If a child of school age is fussy about trying new foods, then using rewards and social praise is an effective way of persuading them to test new tastes.
  • Setting healthy eating preferences early on is best to keep healthy eating going into childhood. Even if eating habits go awry in teenage years, many return to their early healthy eating habits as adults.

I thought this raised some interesting points, such as the persistance needed to introduce new tastes during a sensitive time window, and was worth highlighting.

It’d be interesting to know how these environmental factors interact with genetically influenced preferences, such as whether early exposure to broccoli, sprouts or cabbage can moderate the repulsion certain people have towards a compound in those foods. It has been suggested that ageing, smoking or illness may modify this genetically based food preference, and so it would be intriguing to know whether child eating behaviour did so too.

The journey begins…

The spur to start more formally chronicling my scientific take on parenting came from my agreeing to do a report for the excellent Pod Delusion podcast. The report centred on the unsolicited and unsubstantiated advice my partner and I encountered during her pregnancy.

It was a pretty awesome experience becoming a dad for the first time:

Jerry Coyne – evolutionary geneticist and author of ‘Why Evolution Is True’ – wrote recently on his blog about experiences akin to those attributed to a higher power, in which the sheer awesomeness of an event can bring about a sense of transcendence but separate from anything supernatural or religious, and this was definitely one of those for me.

As someone with a scientific background, I have always been driven to take a rational, critical look at claims. But now with a child to look after, things seem more weighty:

I could trust that millions of years of evolution has provided me with a paternal instinct that will kick in as and when needed, thereby ensuring that the fitness of my offspring will be increased. However, with such responsibility, ‘winging it’ is a little scary [and …] I would like to know the decisions I make as a parent have the backing of more than a ‘gut feeling’ or the instruction of age-old religious doctrine.

I felt as though of lot of the unsolicited advice I had received was supported by mysticism, hearsay or anecdotal evidence. I could also see some biases creeping in:

Many of these intuitions get perpetuated by a massive confirmation bias – all the people who guessed a boy said “I told you so, I just knew it, the way you were carrying that bump it must have been a boy”, whilst the other remaining half, who had predicted a girl, remained strangely silent and seemed to forget their prediction altogether.

I mentioned this because it is apparent when it comes to psychoanalysis:

there’s a wealth of cod psychological theories to explain someone’s personality with proponents retrofitting individuals who conform to these ideas to support their claim, whilst ignoring all other individuals who don’t.

I could also see some beautiful examples of some common logical fallacies: correlation does not mean causation, sample sizes and statistical power, absolute risk vs. relative risk, and reporting and recall biases. Listen to the report for more details.

My science-trained mind would almost always lead me to query claims, as any critical thinker should:

Whenever I tried to enquire about the evidence or statistics behind a particular claim or point to evidence that – say – there is scant evidence that more births occur during a full moon†, that familiar glazed expression would appear and a cursory muttering of “trust the scientist” might be offered.

†[Interestingly, it seems as though progression through the menstrual cycles leads to variations in the sex ratio, but this of course is unconnected to lunar cycles].

But I realise that it gets very difficult when one is actually placed in the situation of caring for child:

People often want a cast-iron guaranteed to-do list of what to do and what not to do, but scientific guidance rarely works like that. One can make a recommendation on the best available evidence, but those recommendations are liable to change and attitudes and practices need to be flexible enough to shift too. My mum, for instance, listening to the pervading advice at the time, slept me on my front to reduce the chances of Sudden Infant Death Syndrome through choking, but evidence since then has accumulated that shows an increased risk of cot death with front-sleeping and now babies overwhelmingly are slept on their backs.

And I do definitely value experiential advice, but I also appreciate that what works for one baby does not necessarily work for another. I guess that that was my motivation to look towards empirically validated advice to guide us during our rollercoaster, and so I concluded a few things I have picked up already:

  1. Be wary of any sentence that starts, “They say that…”*
  2. Do as I do, not as I say. There is a wealth of evidence that children who witness their parents carry out a particular behaviour – such as smoking, violence, even academic work – are more likely to behave in that way as adults.
  3. Open and honest attitude towards sex. Despite what Nadine Dorries may perpetuate, evidence suggests that when parents take a more positive attitude towards sexuality it can be beneficial for a child’s comfort with their own sexuality. And religiosity appears to have little impact on sexual risk-taking – the bigger influence is parental affection.
  4. Strike a balance. Musical training can be beneficial in attention, cognition, and language development. Early take-up, higher parental support, practice, and friendly rather than technically able music teachers all help, but there is evidence that successful childhood musicians need teachers who are ‘not too relaxed’ but ‘not too pushy’.
  5. And don’t read Mumsnet.**

*[I didn’t elaborate in the recorded report, but normally “they say that…” is followed by something that one person once said, that was based on a sort of hunch which may or may not be generalisable].

**[a cornucopia of anecdotes, ‘just-so’ stories and madly evangelical parents].

So that was my first formal attempt at verbalising some of the thoughts and ideas that came to me during a fairly tumultuous time. I wrote and recorded it during the first couple of weeks of our child’s life, so any glaring errors I will blame on sleep deprivation. More shall come as I look ahead to rearing this bundle of squidge.

[Note: more links to original studies will be added].