Ketones in urine during pregnancy

By trimester

Weeks 1–13

1st trimester

Morning sickness and longer gaps between meals can produce urine ketones. Persistent vomiting, weight loss, reduced urination, dizziness, or inability to keep fluids down needs same-day assessment rather than interpretation from a home strip alone.

Weeks 14–27

2nd trimester

Ketones may appear after fasting or illness, including around glucose testing, but a urine value cannot show current blood ketone burden or acid-base status. People using insulin need a written sick-day and ketone-testing plan from their diabetes team.

Weeks 28–birth

3rd trimester

Pregnancy becomes more prone to rapid ketone production, and diabetic ketoacidosis can occur at lower glucose than outside pregnancy. Vomiting, abdominal pain, rapid or difficult breathing, confusion, or positive ketones with illness requires urgent clinical testing.

What does the evidence show for ketones in urine?

• Urine ketones appear when the body uses fat because available glucose is insufficient. Small amounts can occur after fasting, vomiting, or low carbohydrate intake, while high ketones with diabetes can signal ketoacidosis and require urgent assessment. 1
• In an observational cohort of 187 pregnant participants with overweight or obesity, 22 percent had fasting urine ketones at either 16 or 28 weeks and 8 percent had ketones at about 36 weeks. The selected cohort measured prevalence, not severity, cause, or pregnancy effects. 2
• Pregnancy accelerates ketone production during fasting. Diabetic ketoacidosis can develop faster and at lower glucose levels than outside pregnancy, including glucose near 200 milligrams per deciliter, so glucose alone cannot safely exclude it when symptoms and ketones are concerning. 3
• Urine strips mainly measure acetoacetate and give a semiquantitative category rather than a real-time severity value. They may lag behind current physiology and may underestimate acute ketoacidosis because beta-hydroxybutyrate, the dominant ketone in severe ketoacidosis, is not directly measured. 4
• A systematic review of 66 reports found that pregnancy-related diabetic ketoacidosis included both classic and euglycemic presentations, commonly with nausea, vomiting, thirst, frequent urination, and abdominal pain. Most evidence came from case reports or small series, so frequencies are vulnerable to reporting bias. 5

When should I call my provider about ketones in urine?

Go to urgent or emergency care for positive ketones with diabetes and persistent vomiting, abdominal pain, rapid or difficult breathing, fruity-smelling breath, confusion, fainting, or severe drowsiness. Inability to keep fluids down, reduced urination, marked weakness, or ongoing weight loss also needs same-day assessment because pregnancy can progress to dehydration and ketoacidosis quickly. None of these lists replace your own judgment: if this symptom worries you, that on its own is enough reason to check in with your healthcare provider.