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If Morning Sickness is associated with fewer miscarriages and higher IQ babies – should it be treated?

Dr Raj Persaud and Dr Nicholas Morris


DSCN0927The many myths surrounding morning sickness are being wheeled out yet again, given the news that a Royal is suffering from it.


First of all ‘morning sickness’ is misnamed as it only occurs in the morning in less than 20% of women. Despite reassurances currently being published that the Duchess’s torment is going to be very temporary, in fact only half of women with nausea and vomiting during pregnancy are completely relieved by 14 weeks’ gestation. Plus it can be extremely debilitating with up to a quarter of women, in one study, with symptoms, requiring time off work as a result.


Miserable though it may be to experience as a condition, in fact ‘morning sickness’ (if it’s not of the rarer more severe kind), oddly enough, can be good news for a pregnancy. It’s associated with lowered risk for miscarriage, preterm birth,  low birth weight, and perinatal death. However it can also be associated with serious medical conditions which need to be screened for and treated, but most often occurs in medically normal pregnancies.


In 2009 a study published in ‘The Journal of Pediatrics’ from the Hospital for Sick Children, Toronto, provoked controversy when it found nausea and vomiting during pregnancy was significantly associated with better IQ test results in children aged 3 to 7 years after delivery. A battery of psychological tests were involved including  measures of intelligence, neurocognitive abilities and behavior problems.


The study entitled ‘Long-term Neurodevelopment of Children Exposed to Maternal Nausea and Vomiting of Pregnancy and Diclectin’ – by Irena Nulman, Gideon Koren and colleagues, found the more severe the Nausea and Vomiting during Pregnancy, the better the child’s eventual scores across the range of tests.


No one knows exactly why nausea and vomiting during pregnancy is generally good for the foetus, but this has led to a ‘Maternal and Embryo Protection Hypothesis’, which argues its purpose may be to shield the mother from contaminated food, so protecting the developing foetus against potentially threatening toxins and bugs.


Some have hypothesised that raised hormone levels during pregnancy, such as oestrogen and Human Chorionic Gonadotrophin levels make the smell or olfactory system in the female brain hyper-sensitive. One theory is that it’s smells which might be the primary driver of nausea and vomiting during pregnancy, and extra-sensitivity to odours protects mothers from imbibing hazards. It is also established that Asian women have more troublesome vomiting and this seems to be due to the structure of Human Chorionic Gonadotrophin. DSCN0903


Many features of Nausea and Vomiting during Pregnancy suggest an evolutionary adaptive design. For example, Samuel Flaxman and Paul Sherman from the Dept of Neurobiology and Behavior, Cornell University, contend it’s therefore no accident it tends to occur during the most sensitive period of embryogenesis (weeks 5–18). They also point out in their commentary in the academic journal ‘Trends in Ecology & Evolution’, it causes physical expulsion of and subsequent aversions to the foods that are most likely to be hazardous including meats, caffeinated beverages and pungent vegetables. They also note the intriguing absence of Nausea and Vomiting during Pregnancy in seven societies on four continents lacking such dietary triggers.


Another theory is that the food aversion is completely incidental and an unwanted side-effect ,as it’s a direct effect on the foetal brain or the placenta of high levels of hormones of pregnancy which cause nausea, which is why there appears to be an association with baby benefits.


Rachel Huxley from the Institute of Health Sciences, University of Oxford, in a paper entitled ‘Nausea and vomiting in early pregnancy: Its role in placental development’ suggests that morning sickness is linked to secretion of hormones that rise during pregnancy, and which divert nutritional resources away from the mother and preferentially to the developing placenta. She points out in her paper, published in the academic journal ‘Obstetrics and Gynaecology’ that in animal husbandry it’s common practice to relocate ewes to poor pastureland for the first few weeks of pregnancy, as a period of restricted food intake appears to stimulate placental development.


Whether nausea and vomiting has a natural protective or positive purpose during pregnancy raises a conflict for doctors as to whether women should be treated to suppress symptoms, or encouraged instead to ‘ride them out’. This is made all the more difficult given the long history of some anti-nausea treatments when ingested, causing congenital problems. Severe Nausea and Vomiting of Pregnancy, otherwise known as hyperemesis gravidarum, should definitely be treated as it can result in life-threatening malnutrition and liver damage, but it’s rare, and affects less than 1% of pregnant women. The most dangerous consequence is for the woman to suffer vitamin deficiencies and this can cause maternal brain damage.


In a study entitled ‘Understanding the Stigma of Hyperemesis Gravidarum: Qualitative Findings from an Action Research Study’, Zoe¨Power, Ann Thomson, and Heather Waterman from the University of Manchester point out the treatment of women with this serious condition varies from hospital to hospital, particularly as in the UK, there remain no national guidelines.DSCN0897


The most common experience described by women with hyperemesis gravidarum in this study, published in the academic journal ‘Birth’,  was constant nausea and very frequent vomiting, with an inability to tolerate almost any diet or fluids without throwing up. Duration of symptoms could extend from days to weeks and months. Extreme hunger and thirst impossible to alleviate, weakness and general distress were commonly reported. Often it seems nothing much helped except perhaps rehydration by intravenous infusion. Feeling defeated was common. The symptoms frequently ended up having a strong emotional impact – but it seems health professionals often took the opposite, unhelpful and even stigmatising view, and seemed to assume that the vomiting was caused by psychological problems.


At its most extreme, historically, nausea  and  vomiting during pregnancy were stigmatised as  psychological  manifestations  of an  unwanted pregnancy. The more modern scientific view, which is that there are most likely biological and even genetic causes, seems to be taking a long time to percolate to the front line of clinical care.


Women suffering from so called normal nausea and vomiting are often desperate, and any safe treatment, particularly those which doesn’t involve taking something, given the risks to the foetus, should be welcomed.


Elisabeth Hyde has published an interesting clinical trial showing the benefits of acupressure in this condition in the Journal of Nurse-Midwifery, but there appears little follow up of this kind of research.


Twenty-one women in the first 12 weeks of pregnancy were studied in an investigation which found an intriguing link between body sway during pregnancy and morning sickness which led the authors to propose a novel therapy. The paper entitled ‘Standing body sway in women with and without morning sickness in pregnancy’ and just about to be published by Yawen Yu, Hyun Chae Chung, Lauren Hemingway and Thomas Stoffregen from the University of Minnesota  in the academic journal ‘Gait & Posture’ suggested pregnant women who adopted a wider stance when standing and walking, might experience less morning sickness.


This condition also responds to vitamin supplementation, acupuncture and acupressure. These treatments can also improve mood during pregnancy and the emotional impact of nausea and vomiting during pregnancy  is extremely important.


Dr Nicholas Morris is a Consultant Obstetrician and Gynaecologist working in Private Practice in Central London. Dr Raj Persaud is a Consultant Psychiatrist working in Private Practice in Harley Street, Central London.


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