Some of what causes gestational diabetes in pregnancy is understood but it isn’t always clear why some women have a problem with it while others don’t. What is known is that almost every woman will develop some degree of glucose intolerance that is impaired by the normal hormonal changes caused by pregnancy. That indicates that almost all pregnant women have higher than normal blood sugar. But this alone is not enough to explain what causes gestational diabetes in pregnancy. It does usually happen in the last trimester.

While pregnant, some hormone levels are increased, particularly those made in the placenta. This is needed to help pass nutrients from the mother to the baby. Meanwhile, other hormones in the placenta are produced to help the mother from developing low blood sugar levels. The way they work is by stopping the actions of insulin. Part of what causes gestational diabetes in pregnancy …

It is fairly easy to understand what causes diabetes in pregnancy to develop at a higher rate in women. It all boils down to glucose. Glucose is the body’s main nourishment, developing as the result of digesting food. Since we all digest food, we all produce glucose. When pregnant, the mother’s body must also provide glucose to supply the baby’s needs. The glucose is passed from the mother to the baby through the wall of the placenta. This is the baby’s sole source of nourishment.

The placenta makes hormones to aid the development of the fetus, but these same essential hormones also make it more difficult for the mother’s body to use up the insulin. After about 19 or 20 weeks, the placenta starts producing a lot more of these hormones that are “anti-insulin”, and is the beginning of what causes pregnancy diabetes.

If too many of these anti-insulin hormones …