Although every pregnancy is potentially at risk and should be protected by taking preconceptional folic acid, some women have an increased risk of their pregnancy being affected. This includes:
- Couples where either partner has spina bifida, or a family history of NTD.
- Women that have had a previously affected pregnancy.
- Women that have diabetes.
- Women taking certain anticonvulsants for epilepsy.
- Women with coeliac disease or other conditions that affect the absorption of nutrients.
- Women that are very overweight (ie BMI over 30)
Any women falling into one of these categories should make an appointment to see their doctor before trying to get pregnant. They will also need to take a higher 5mg dose of folic acid which their doctor may need to prescribe. This will significantly reduce their risk of having a pregnancy affected by an NTD.
Being very overweight/obese significantly increases the risk of adverse birth outcomes for both mother and baby (7 fold risk increase), and can increase the risk of NTD. The risk of NTD increases incrementally with the severity of obesity, rising from 1.7 fold to >3 fold between obesity and severe obesity. Although the mechanism by which obesity increases the risk of NTD is not fully understood, it is thought to be related to problems with glucose control and metabolism. It is vital for women to achieve a healthy weight before trying to conceive, i.e. a healthy BMI, between 19-29), and that they are supported with realistic weight reduction plans and ongoing support mechanisms wherever possible. Women that already overweight when they fall pregnant should not try to diet whilst they are pregnant, but should monitor their weight gain to ensure that they don’t gain excessive weight. Further guidance for women that are overweight can be found here
Women with Diabetes experience a 2 fold increase in their pregnancies being affected by birth defects. The risks increase significantly where women have poor glycaemic control preconceptionally, and in early pregnancy. It is vital that women with diabetes ensure that their blood sugar is well managed before trying to conceive, and that they achieve a healthy BMI prior to pregnancy. Diabetic women should also speak to their doctor/specialist to ensure that any necessary changes are made to their treatment and medication. Girls with diabetes should be educated from adolescence about the additional risks during pregnancy, and the importance of avoiding unplanned pregnancy by ensuring that effective birth control methods are employed. Further guidance for women with diabetes can be found here
Some seizure medications are unsuitable for use during pregnancy, and act as anti-folates, preventing the effective metabolism of folic acid.It’s vital that women with epilepsy speak to their doctor/specialist before they try to conceive to ensure that any changes that might be necessary can be made to their medication. If medications need to be changed it may take several months to adjust to the new medication. This may be difficult as once a woman has reached the decision to have a baby, they generally don’t want to wait months before trying, but women with pre-existing health conditions should be prepared to be flexible and ready to change their pregnancy plans to ensure the best health for their future baby. Further guidance for women with epilepsy can be found here
Poorly controlled coeliac disease can increase the risk of developing pregnancy related complications, including increasing the risk for NTDs due to malabsorption of folic acid and B12. Women with coeliac disease and other conditions that affect absorption should speak to their doctor before trying to conceive to ensure that they are getting the required amount of essential nutrients to support a healthy pregnancy. As women with coeliac disease are unable to eat gluten, current fortification strategies do little to support this sub-group of women, so ensuring supplementation at the correct dose is vital to maximise risk reduction in these women. Further guidance for women with coeliac disease can be found here
Families with a history of NTD
Women of certain ethnic backgrounds are shown to have an increased risk of NTD, including women of Celtic, Northern Chinese, Cree, Hispanic and Sikh heritage. The exact reason for this increased risk is unknown, but is thought to be a combination of genetic and cultural dietary factors.
Other factors which may contribute to NTD risk
Smoking and alcohol consumption
We know that poor lifestyle choices have a significant part to play in increasing adverse birth outcomes for both mother and child. These lifestyle factors will become even more significant when we look at the potential for prevention of hydrocephalus. However, whilst smoking and alcohol consumption are known to increase the risk of small for gestational age, preterm birth, stillbirth, sudden infant death and Foetal Alcohol Syndrome, they can also affect the absorption of folic acid, which consequently may mean that they could also increase the risk of NTD.
Increased body temperature
Some evidence suggests that increased body temperature (hyperthermia) in the early weeks of pregnancy may increase the risk of spina bifida. Elevating your core body temperature, due to fever or the use of saunas or hot tubs, has been associated with increased risk of spina bifida. For this reason women are advised to ensure that they are in good health before trying to conceive, and if they become unwell, to stop trying to conceive until they have fully recovered. Women are also against the use of hot tubs and saunas whist they are pregnant or trying to conceive.
As we know, not all NTDs are folic acid preventable. Some cases are known to be genetic, others relate to women in higher risk groups and others remain unknown. The possible involvement of environmental factors such as industrial chemicals, solvents, fungicides and pollutants is an area currently under research in an attempt to uncover another piece in the NTD puzzle.