Ketones in Urine During Pregnancy

Ketones in urine during pregnancy are often innocuous, but they can indicate a significant disease. Ketones (also called ketone bodies) are an alternative energy source for your body's cells, used when glucose is not available or can't be used. Ketones appear in the urine and blood during situations such as prolonged fasting, vomiting, and extreme exercise. Ketones in urine during pregnancy should not be ignored as they can be a sign of gestational diabetes and other disorders.

About one in five women have ketones in urine during pregnancy. The body produces more ketones during pregnancy, especially in the third trimester, because of increased energy needs [1]. Other metabolic changes during pregnancy that promote ketone production are increased insulin resistance, accelerated fat breakdown, and more glucose production in the liver (gluconeogenesis). Ketosis is more likely among pregnant people, especially those with abnormal glucose metabolism [2].

High Ketones in Urine Pregnancy

The three types of ketone bodies are acetoacetate, acetone, and beta-hydroxybutyrate [2]. They're produced in the body by breaking down fats. Most cells in your body prefer to use glucose as an energy source; ketones are an alternative energy source when glucose and other carbohydrates are not available.

Gestational diabetes is an important cause of ketones in urine during pregnancy. But ketones in urine during pregnancy are not diabetic always; they can be a sign that you're not consuming enough calories and carbohydrates. Some reasons are vomiting, fasting or long gaps between meals, and eating disorders [3].

Ketones are present in the blood under normal circumstances, too. The normal ketones levels are less than 0.5 millimoles/liter. Levels greater than 1.0 millimole/liter are defined as hyperketonemia, and levels more than 3.0 millimoles/liter indicate ketoacidosis [2].

Ketone blood levels higher than normal is called ketosis. A light state of ketosis is not a dangerous situation. However, very high levels of ketones in the blood cause it to become acidic, a dangerous condition called ketoacidosis. This happens most often with untreated or improperly treated type 1 diabetes. High concentration of ketone bodies in the bloodstream cause ketones to appear in the urine (ketonuria).

Are Ketones Harmful During Pregnancy?

Ketones in the urine don't harm your baby. However, ketonuria is a sign of high ketone levels in the blood. Ketones in the blood can cross the placenta and reach your baby.

Ketones in the urine during pregnancy have been associated with some adverse outcomes — reduced childhood intelligence quota (IQ), oligohydramnios (diminished amniotic fluid), fetal heart rate irregularities, and non-reactive non-stress tests [1]. Birth defects like cleft lip, cleft palate, heart defects, and malformations of the digestive and nervous systems are associated with high ketone blood levels. The effects on the baby are worst in early pregnancy [2].

However, it is not certain that the adverse outcomes are caused by ketones. The disorder causing ketonuria may be responsible for them.

Diabetes is a frequent cause of ketones in urine during pregnancy. If not prevented, it can lead to diabetic acidosis, electrolyte imbalances, kidney failure, heart failure, and brain dysfunction [2].

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