The environment in the uterus is not a passive one. The infant is exposed to and reacts to the mother's intake of medications, alcohol, toxins, and, of course, nutrition. The development and future functioning of the baby's internal organs, as well as his or her brain development and the abilities to think, reason, and feel are all subject to positive and negative influences at various times during pregnancy.
Compared to the lean mothers, obese mothers showed abnormally high insulin and blood sugar levels.
During fetal development, the hormonal and biochemical systems that maintain proper balance of all the substances in the blood and tissues (hormones, enzymes, sugar, salts etc) of the growing child and future adult may be influenced as genes or parts of genes are turned on or off, or modified in response to the intrauterine environment. This is why maternal physical and emotional health and nutrition throughout the pregnancy can be so profoundly important.
In the June issue of Diabetes Care, researchers explored how the obesity of a pregnant woman affects the blood sugar regulation system of the fetus. Previous studies have shown an increase in both obesity and type 2 diabetes in children born to women who are either obese and/or diabetic during their pregnancies. Other studies have shown that infants of obese mothers have increased fat mass compared to infants of lean mothers, even if the overweight mothers don't have diabetes. They also are more than twice as likely to develop abnormalities of insulin, glucose and blood fats by age 11 than those born to lean mothers.
In this study, the researchers looked at how well the glucose regulation and insulin systems were functioning in fetuses of obese mothers compared to fetuses of lean mothers. The study group was made up of 52 lean pregnant women and 68 obese pregnant women. All the mothers-to-be were carrying a single infant and were undergoing elective C-section. Umbilical cord blood was obtained at the time of delivery as a measurement of levels of sugar and insulin in the fetal blood. The mothers' insulin and sugar levels were also tested.
Compared to the lean mothers, obese mothers showed abnormally high insulin and blood sugar levels. The umbilical cord blood samples showed that their fetuses had similar abnormalities of insulin and blood sugar. Although the fetuses of obese mothers did not weight significantly more than those of lean mothers, they did have more fat in their bodies.
The presence of high insulin and high sugar is a sign of insulin resistance, which means that although the body produces insulin, it is not used effectively. It is a condition that can lead to diabetes. Normally, as food is digested and blood glucose (sugar) rises, the pancreas produces insulin. Glucose is absorbed into the blood stream and delivered to muscle, fat, and liver, and insulin helps the cells of these organs use the glucose to provide energy for normal functioning.
However, if the muscle, fat, and liver cells don't respond to the insulin normally (are resistant), the glucose fails to enter the cells, the pancreas continues to sense a high blood sugar level and responds by producing even more insulin. When the blood glucose remains high and the pancreas can't provide enough insulin to overcome this level, the conditions are created for the development of diabetes.
When the pregnant mother's insulin is not working effectively, some of her stored body fats are broken down to their building blocks, free fatty acids. These free fatty acids are carried to the fetus where they can be used to create abnormally high deposits of fat in the developing infant.
Both the obese mothers and their fetuses in this study were more insulin resistant than lean mothers. In fact, the more insulin resistant the mother, the more insulin resistant the fetus. As could be expected, the more insulin resistant the fetus, the larger the amount of fat that was deposited during gestation. Thus, at birth, because of their intrauterine exposure to elevated levels of maternal sugar, insulin and fatty acids, the newborns were already compromised, with risk factors firmly in place for developing type 2 diabetes, unfavorable blood cholesterol, and the many complications of these conditions.
The researchers feel that the message is clear. Obese mothers, whether or not they have diabetes, put their infants at high risk for the development of insulin resistance, future diabetes, and abnormalities of blood cholesterol and fats. They maintain that treating obesity in pregnant women must also be seen as a treatment for the fetus, which may already be showing biochemical changes that may compromise its future health.
Overweight women who are anticipating pregnancy should be aware of the potential risks to their fetuses and should seek medical guidance for safe weight loss both before and during pregnancy. Non-pregnant teenage and young adult women who are obese may also benefit from counseling long before they anticipate pregnancy. Often, motivation to change unhealthy habits gets an extra boost when the future well-being of a child is at stake.