Did you know that even before we are born certain factors can determine our risk of developing chronic, lifestyle-related conditions, such as cardiovascular disease and diabetes, later in life?
It has long been known that genetic diseases arise either from inheriting defective genes from our parents or acquiring a genetic mutation early in development. However, a growing body of research is beginning to shed light on the association between fetal conditions in utero (the womb) and more complex, lifestyle-related, metabolic conditions such as obesity, type 2 diabetes and cardiovascular disease in adulthood.
The first study to show this association came in the late 1980’s, when an epidemiologist called David Barker noted that babies who had been smaller at birth had a higher risk of developing diabetes and cardiovascular disease (1) . Since then, our understanding of the link between fetal growth and adult health has improved significantly. For example, mothers who smoke during pregnancy have a higher risk of giving birth to babies with low birth weight, and these babies are at risk of developing conditions such as asthma and even intellectual impairment later in life (2, 3) . Drinking alcohol during pregnancy can cause problems such as fetal alcohol syndrome, which involves poor fetal growth and facial abnormalities together with problems such as learning difficulties later in life (4).
Importantly, we now know that not only babies who are born with an inappropriately low birth weight (called Small for Gestational Age or SGA), but also those born with an inappropriately high birth weight (called Large for Gestational Age or LGA) are at higher risk of developing metabolic disorders in adulthood (5) . And the most important modifiable risk factors for a baby being born LGA is maternal obesity, maternal diabetes or excessive weight gain during pregnancy (6) .
With currently one in four UK adults being classified as obese, and the number of UK adults classified as diabetic expected to double in 20 years, we are now at a time when a negative spiral of metabolic disease in adults increases the risk of metabolic disease in the next generation at a worrying rate (7) . All of this may seem a bit ‘doom and gloom’, however understanding how maternal health determines fetal growth and wellbeing also means that we have a chance to intervene and improve the health of our children and generations beyond.
How does the health of the mother affect that of her baby?
For a fetus to thrive, it needs a steady supply of nutrients such as glucose (blood sugar) and amino acids (proteins), vitamins, minerals, oxygen and hormones. All of these are provided by the mother via the placenta, which lines the uterus of a pregnant woman and forms the link between the maternal and fetal circulation. In the case of uncontrolled maternal diabetes, far too much glucose passes from the maternal to the fetal circulation, increasing the risk of LGA. In the cases of maternal smoking or maternal hypertension (high blood pressure), the vessels in the placenta become less efficient at delivering oxygen and nutrients to the developing fetus, increasing the risk of SGA (8) .
Interestingly, on the topic of smoking, a recent large scale meta-analysis (a study that compiles results from several similar studies to produce more reliable results) of paternal factors that affect fetal growth showed that paternal smoking significantly increased the risk of SGA as well as a range of developmental abnormalities (9) . In other words, not only the lifestyle of the mother but also that of the father impacts on a baby’s wellbeing in utero and beyond.
What can I do to optimise my health for a potential future pregnancy?
After so much talk about risks and how the health of a mother can impact on that of her baby’s, it is time to bring the discussion back to you, and talk about how you could optimise your health to prepare for a pregnancy, now or in the future.
The good news is that the advice is far from revolutionary; maintaining a healthy weight through a balanced diet and regular physical activity is enormously beneficial in terms of preparing for a pregnancy and beyond. Keeping in mind how important blood sugar control is in terms of fetal development, try to keep your intake of refined sugar and simple carbohydrates low, and instead focus on fruits and vegetables of different colours, lean protein, legumes, and a moderate amount of unsaturated fats. You might want to pay particular attention to your intake of folate, which is naturally found in green leafy vegetables and reduces the risk of neural tube defects a developing fetus. If you are considering a pregnancy in the near future, then the NHS recommends daily 400mcg folate supplements (which should be continued up to 12 weeks of pregnancy) and also avoiding foods such as raw meat and certain soft cheeses. Avoid smoking and keep your alcohol intake low (10) .
You are probably already aware of the benefits of regular exercise, but it is worth mentioning how important physical activity is in pregnancy specifically. A recent review of results from studies of exercise in pregnancy found that regular physical activity decreases the risk of high blood pressure, diabetes and excessive weight gain, and improves cardiovascular fitness. Nothing too surprising perhaps, but gone are the days when pregnant women were advised to keep still and rest over fears that physica exertion could harm their growing baby. Indeed, current advice (for the healthy woman with an uncomplicated pregnancy) is to aim for 150 minutes of ‘moderate physical activity’ per week, similar to the advice given to the general adult population (11) . Of course, pregnancy is not the time to start training for a marathon, and if you are not used to exercise, the advice is to start gradually and avoid exertion beyond the point where you feel too breathless to keep a normal conversation going. For more advice on pre- and postnatal nutrition and training do make sure to check out The Food Medic podcast.
Lastly, it is important to bear in mind that even if we do everything ‘right’ in terms of leading a healthy lifestyle, managing our stress levels, avoiding smoking and taking the recommended folate supplements, a healthy baby can unfortunately never be guaranteed. And it is vital that highlighting how maternal health can affect the health of her baby does not translate into blaming mothers when something goes wrong; I haven’t met a single mother who isn’t trying her hardest to provide the best possible start in life for her baby. We need to keep lifting the taboo that still surrounds questions around women’s health, and are beginning to do so with prominent women like Michelle Obama and Lena Dunham speaking openly about topics such as fertility treatment and endometriosis. But we also need a comprehensive public health strategy that takes into account the importance of preventing metabolic disease not only in our generation, but also in the next. And next time you’re thinking about whether to go for that run or swapping the chips for a salad, maybe bear in mind that healthy decisions that benefit you may also be healthy decisions that benefit your future children.
(1) Hales CN, Barker DJP, Clark PMS, Cox LJ, Fall C, Osmond C, et al. Fetal and Infant Growth and Impaired Glucose Tolerance at age 64. British Medical Journal. 1991;303(6809):1019-22.
(2) Stick SM, Burton PR, Gurrin L, Sly PD, LeSouef PN. Effects of maternal smoking during pregnancy and a family history of asthma on respiratory function in newborn infants. Lancet. 1996;348(9034):1060-4.
(3) Lange S, Probst C, Rehm J, Popova S. National, regional, and global prevalence of smoking during pregnancy in the general population: a systematic review and meta-analysis. Lancet Global Health. 2018;6(7):E769-E76.
(4) Riley EP, Infante MA, Warren KR. Fetal Alcohol Spectrum Disorders: An Overview. Neuropsychology Review. 2011;21(2):73-80.
(5) Carless MA, Kulkarni H, Kos MZ, Charlesworth J, Peralta JM, Goering HHH, et al. Genetic Effects on DNA Methylation and Its Potential Relevance for Obesity in Mexican Americans. Plos One. 2013;8(9).
(6) Kim SY, Sharma AJ, Sappenfield W, Wilson HG, Salihu HM. Association of Maternal Body Mass Index, Excessive Weight Gain, and Gestational Diabetes Mellitus With Large-for-Gestational-Age Births. Obstetrics and Gynecology. 2014;123(4):737-44.
(7) Office for National Statistics. Health Survey for England, 2016: Adult overweight and obesity. Health Survey for England [Internet]. 13 December 2017. Available from: https://digital.nhs.uk/data-and-information/publications/statistical/health-survey-for-england/health-survey-for-england-2016-resources.
(8) Kvalvik LG, Haug K, Klungsoyr K, Morken NH, DeRoo LA, Skjaerven R. Maternal Smoking Status in Successive Pregnancies and Risk of Having a Small for Gestational Age Infant. Paediatr Perinat Epidemiol. 2017;31(1):21-8.
(9) Oldereid NB, Wennerholm UB, Pinborg A, Loft A, Laivuori H, Petzold M, et al. The effect of paternal factors on perinatal and paediatric outcomes: a systematic review and meta-analysis. Human Reproduction Update. 2018;24(3):320-89.
(10) Stephenson J, Heslehurst N, Hall J, Schoenaker D, Hutchinson J, Cade JE, et al. Before the beginning: nutrition and lifestyle in the preconception period and its importance for future health. Lancet. 2018;391(10132):1830-41.
(11) University of Oxford Physical Activity and Pregnancy Study Group. Physical Activity and Pregnancy Infographic Study Interim Report 2016. Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/622623/Physical_activity_pregnancy_infographic_guidance.pdf.