By Neus Ferrando Gilabert BSc, MSc (embryologist).
Last Update: 11/02/2015

Gestational diabetes is a type of diabetes that some women suffer during pregnancy. Unlike other types, the gestational one is not caused by a lack of insulin, but by a blockage on its functioning, produced by the hormones secreted during pregnancy.

The different sections of this article have been assembled into the following table of contents.


It is known that the placenta produces some hormones that are necessary for fetal development. These hormones block the action of insulin the mother has produced, creating what is known as insulin resistance. The typical response against this effect is an increase in insulin production; if it happens, the pregnant woman may develop gestational diabetes. Blood glucose is not transformed in energy, stocking up until it reaches concerning levels. This alteration is called hyperglycemia.


This type of diabetes affects 4% of women and usually appears at the 20th week of pregnancy, being however more frequent during the 28th week of gestation. In most of the cases, glucose levels go back to normal after delivery, having a prevalence of 1-3%.

Nevertheless, if the mother has had diabetes during her first pregnancy, there is chance she suffers it again if she gets pregnant again. Sometimes, pregnancy allows the diagnosis of type-1 and type-2 diabetes. It is hard to discern whether these women had gestational diabetes or they begin to manifest the sypmtoms during pregnancy. In both cases, monitoring the treatment after the delivery is strongly advisable.

Risks for the baby

Since gestational diabetes is a condition that tends to appear in the final stages of pregnancy, when the body of the unborn is formed, it has to be controlled to prevent the development of malformations or defects in the baby once he/she is born.

It seems quite self-evident that not addressing diabetes may severely affect the baby; mother’s blood glucose can be transferred into the baby through the placenta, producing more insulin. Given that the baby is receiving more energy than normal, the energy is stored as fat, and that can originate macrosomy, i.e. a full-size baby.

These babies can suffer injuries during a vaginal delivery, being necessary to perform a cesarean.

Babies whose mother had gestational diabetes may have breathing problems, low blood sugar, and jaundice during their first weeks of life.


Fortunately, gestational diabetes can be monitored through diet and exercise.

The doctor usually recommends to control the blood sugar intake on a daily basis. In some cases, it is required to inject insulin in order to reduce glucose levels. Besides, it is also advisable to have montlhy ultrasounds from the 28th week onwards to detect the appearance and/or evolution of macrosomy.

Despite gestational diabetes is a cause for concern, it can be treated and controlled, hence protecting the health of both the baby and the mother.

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Authors and contributors

 Neus Ferrando Gilabert
BSc, MSc
Bachelor's Degree in Biology from the University of Valencia (UV). Postgraduate Course in Biotechnology of Human Assisted Reproduction from the Miguel Hernández University of Elche (UMH). Experience managing Embryology and Andrology Labs at Centro Médico Manzanera (Logroño, Spain). More information
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One comment

    1. Samantha398

      Hi there! I’m 37 weeks pregnant and after my last visit to my GYN/OB, they told me that I have excessive amniotic fluid (polyhydramnios), but when I was 33 weeks pregnant it was okay 🙁 How is this possible? What are the consequences? I’m excessively concerned, does it lead to miscarriage? For my own peace of mind, give me an answer ASAP! Thanks