Diet during conception and pregnancy
Dr Kate Marsh is an Advanced Accredited Practising Dietitian. She is co-author of The Bump to Baby Diet and credentialed diabetes educator based in Sydney.
1. There is an increased interest in diet and lifestyle to assist conception. What does the evidence say?
There is definitely an increased interest in this area, and for good reason. Optimising diet, lifestyle and weight prior to conception not only improves fertility but also increases the chances of a healthy pregnancy and can impact the long-term health of a child. In particular, both peri-conceptual and in-utero nutrition can impact a child’s future risk of obesity and metabolic disease.
2. Is it necessary to avoid sugar to increase chances of conception?
I don’t believe there is any evidence to show that sugar intake per se influences fertility. However, women who are planning a pregnancy should be aiming for a nutrient-dense diet and optimising their weight and this leaves little room for a lot of added sugars, which provide energy without nutrition. Natural sugars in fruit and dairy foods, and small amounts of added sugar as part of a healthy diet aren’t likely to be a problem.
3. What are the key health issues facing pregnant women in Australia?
Increasing rates of obesity are a particular concern, as being overweight can impact fertility and pregnancy outcomes. Women who are overweight or obese are not only less likely to fall pregnant, but when they do, they are more likely to develop gestational diabetes, hypertension and pre-eclampsia. They have a higher risk of miscarriages, caesarean section and traumatic delivery. Infants born to mothers who are overweight have a higher risk of stillbirth, shoulder dystocia, preterm delivery, neonatal death, and congenital abnormalities. They are also more likely to develop obesity and metabolic disorders in the future.
Alongside weight, the risk of insulin resistance and type 2 diabetes are also increasing, and coupled with many women having children later in life, the incidence of gestational diabetes is rising, with significant implications for both maternal and infant health.
4. What general dietary advice can women follow to enhance their own health and the health of their baby?
Optimising nutrition, lifestyle and weight prior to conception can significantly improve the chances of falling pregnant and of having a healthy pregnancy. It can also reduce the child’s risk of metabolic and weight problems later in life.
This means adopting a well-balanced nutrient-rich diet, exercising regularly, losing weight if overweight, quitting alcohol, ceasing smoking and limiting caffeine. Managing blood glucose levels and weight gain during pregnancy are also very important.
5. Is there any evidence that eating sugar during pregnancy is harmful?
A mother’s blood glucose levels during pregnancy are directly correlated with a baby’s growth rate in utero. This means that blood glucose levels that are too high or too low can impact fetal growth, and may result in a baby who is born small or large for gestational age. Both small and large babies have an increased risk of childhood obesity, as well as higher risk of metabolic diseases such as diabetes and hypertension in adulthood. Therefore, optimising the glucose environment in utero may reduce a child’s risk of metabolic problems later in life. This requires attention to both the quantity and quality (GI) of carbohydrate consumed, not just sugar intake.
High glucose concentrations during pregnancy are also implicated as one of the causes of birth defects including neural tube defects (NTDs). This is particularly the case in the early stages of pregnancy, when the embryo has no beta-cells and is unable to secrete insulin or regulate their own glucose levels. One study found a two-fold increased risk of NTDs in women with a higher periconceptional intake of sucrose and high GI foods but a more recent study by the same authors found no relationship with sugar intake, including intakes of sucrose, glucose and fructose. Several other studies have shown an association between dietary GI and risk of birth defects.
6. What is your advice to pregnant women about sugar in their diet?
I would recommend focusing on nutrient dense meals and snacks, which doesn’t leave much room for added sugars. There’s no need to avoid the natural sugars in fruit and dairy as the sugars in these foods have a low GI and come along with other nutritional benefits. To avoid excess gestational weight gain while still ensuring adequate nutrition for pregnancy, foods with little nutritional value, including those high in added sugars, would be best minimised.
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