A few weeks into pregnancy everything you ever thought you’d want to eat to keep your baby healthy goes out the window. You find yourself wandering around supermarkets not knowing what to put in your trolley. Kitchens become battlefields. Opening the bin. Cooking smells. Opening the fridge. Leftovers. Perfectly innocent, recently opened jars scream out BACTERIA!!! And must be immediately jettisoned. But the BIN…how to open the BIN?
It’s not known why women experience nausea early in pregnancy. Research points to a variety of possible causes rather than one definitive answer. Is it a protective mechanism ? Is the strong gag reflex that can make it hard to clean our teeth or swallow our vitamins a mechanism to protect the foetus from toxins?
Some experts suggest morning sickness could be an evolutionary adaptation. Could a heightened sense of smell help protect us from food poisoning? If you only want to eat rice cakes, mashed potato and dry toast your chances of getting e-coli poisoning are much lower. With today’s high standards of food hygiene – fridges, freezers and sell-by-dates women have very little to worry about. In comparison, our ancestors would have been in much more danger from putrefying food – although we are rightly advised not to eat raw eggs, pate and sushi just in case. (1)
A hyper-sensitive firewall to protect the baby from external danger makes perfect sense. It’s at this stage of the baby’s development when the foetus is at its’ most defenceless. When even a chemical ‘nano’ particle could be potentially harmful. Cells are dividing rapidly. DNA and RNA are working overtime to lay down the blueprint of a perfectly formed human being. If anything goes wrong now it could be more serious consequences than later on.
Before the placenta is fully up and running the baby is completely dependent on its mother’s detoxification capacity. The liver has a highly complex detoxification system of multiple enzymatic pathways which neutralise, package and ship toxins out of the body via the bile, gut and urine. Is this why we go off coffee? Which can slow down enzymatic pathways. Go off broccoli and kale which can speed them up.
Another reason a pregnant woman may feel ‘hung over’, ‘toxic’ and deeply exhausted during the first trimester is because her detoxification pathways are stretched to the limit. Her liver has to break down and safely process everything she consumes, touches and breathes in– exhaust fumes, hair dye or the whiff of cigarette smoke or alcohol on her partner’s breath. And that’s in addition to safely detoxifying a cocktail of by-products of the baby’s fantastically rapid growth and development. How a woman copes with this mammoth task will be highly individual and to an extent genetically driven. Some women detoxify certain chemicals and compounds quickly, some slowly or more efficiently than others. (2)
How a pregnant woman experiences morning sickness may also be impacted by her diet. How well she ate before she conceived. How well she’s managing to eat now. Is she low on nutrients, like B6 and its cofactor, zinc? Both are needed in larger amounts than normal to help metabolise the flood of extra hormones and digest protein, fats and carbs. Most women find eating quick-release carbs and fruit helps their symptoms. As does eating little and often. Blood sugar regulation is hormonally altered throughout pregnancy, and especially in early pregnancy. Low blood sugar symptoms are common. Women can feel dizzy, faint, irritated and nauseous as soon as they get hungry. Keeping topped up with a ‘mouthful or two of something’ every two hours or even more every hour helps.(3)(4)
How tired or stressed a pregnant woman is also has an impact. Morning sickness and nausea symptoms are always much worse when stressed and overtired. If you sleep badly or feel stressed you immediately feel worse. And there can be a lot to be stressed about. You may need to keep their pregnancy secret from friends and colleagues. You may worry your boss will find out or be concerned about the impact on your relationship; body image; or other children. You may be carrying the burden of a previous pregnancy loss or have a toddler at home or be juggling a demanding job.
Hormonal overload is also thought to play its part. A trio of dynamic pregnancy hormones – Human Chorionic Gonadotropin (hCG), progesterone and oestrogen radically transform how we look, feel and think within the first few weeks of conception. Is it a coincidence that when nausea is at its height midway through the first trimester hCG levels also peak?
This is the hormone which lights up our home pregnancy tests a couple of weeks after we miss a period. Good levels of hCG are linked to reduced miscarriage rates. It supports the corpus luteum to continue to make progesterone and maintain the lining of the uterus. It influences a woman’s immune system so it doesn’t reject the foetus and kick starts the development of the placenta which will later support the baby throughout the rest of the pregnancy.(5)(6)
Incredibly high levels of oestrogen and progesterone are also implicated. Oestrogen stimulates rapid growth but also has a powerful effect on brain altering hormones like serotonin and dopamine which affect mood, appetite, food cravings and nausea. Gastric emptying is slowed down. We feel fuller more quickly. Food sits in our stomachs and makes us burp and feel sick. Unusually high levels of progesterone, needed to maintain the pregnancy, also have the unwanted side effect of slowing down transit time in the gut and contributing to constipation. (7)
There are many possible reasons why women have morning sickness. And probably the causes are multiple. Any definitive research is limited. Possibly because early pregnancy is a very delicate, controversial and difficult time to carry out medical research. The fact that the last time a major drug, Thalidomide, was used to alleviate morning sickness, in the late 50’s, resulted in severe birth defects and a hugely distressing scandal and law suit may be a factor. GPs can prescribe antihistamines, anti-anxiety and anti-sickness medications but otherwise; mild to moderate morning sickness is considered normal: is safe for both mother and child, and just something women ‘have to get on with’.(8)
Morning sickness is very different to a more severe form of pregnancy nausea called Hyperemesis Gravida. HG can be dangerous to both women and their babies. And does need to be monitored carefully by your medical team. Women with HG may be unable to hold down any food or fluids. They may also need periods of hospitalisation and IV drips to reduce the risk of severe dehydration and kidney failure.
Recent genetic research to find the cause of HG, which often runs in families, has come up with a link to a blood protein called GDF15, could also provide a clue to milder forms of morning sickness as well. Research proved that the more Growth Differentiation Factor 15 present in the blood of pregnant women the stronger were their morning sickness symptoms. Another protein called IGFBP7 which influences appetite and placental development also stood out. Giving researchers hope that, in the future, blocking the action of GDF15 may be a potential therapy for HG and an explanation for morning sickness.(9)