Dehydration in Early Pregnancy

Dehydration in early pregnancy is a deficit of body water in the first trimester, most often from vomiting, diarrhoea, poor intake or fever. It matters because it lowers uterine perfusion, causes electrolyte loss and kidney injury, and may hide an infection such as malaria or pyelonephritis.

• Risk factors: nausea and vomiting of pregnancy, gastroenteritis, urinary infection, hot climate, malaria.
• Pregnancy increases fluid requirement by about 300 mL daily.
• Easily corrected when found early.

Women have thirst, dry mucous membranes, reduced urine, dizziness and tachycardia, with reduced skin turgor in severe cases.

• Dark concentrated urine.
• Orthostatic fall in blood pressure above 20 mmHg systolic.
• Differential diagnosis: hyperemesis gravidarum, gastroenteritis, malaria, pyelonephritis, diabetic ketoacidosis, Addison disease.
• Complications: acute kidney injury, electrolyte disturbance, venous thrombosis, preterm uterine activity, miscarriage, shock.

The approach is clinical assessment of volume status with tests for cause and complications.

• Pulse, blood pressure lying and standing, capillary refill, urine output.
• Urine dipstick for ketones, specific gravity, nitrites and leucocytes.
• Urea, creatinine, sodium, potassium and glucose.
• Malaria test, full blood count, ultrasound for pregnancy location and viability.

The principle is rehydration, correction of electrolytes and treatment of the cause.

• Supportive: oral rehydration solution 200 to 300 mL after each loose stool and 2 to 3 litres over 24 hours for mild to moderate dehydration; small sips every 5 minutes if vomiting; urinary output charting.
• Pharmacological: for moderate to severe dehydration give sodium chloride 0.9 percent 1 litre IV over 1 to 2 hours, then 1 litre over 4 to 6 hours; add potassium chloride 20 mmol per litre if potassium is below 3.5 mmol/L; metoclopramide 10 mg IV 8-hourly for vomiting; thiamine 100 mg oral or IV daily if vomiting exceeds 3 weeks; for shock give Ringer's lactate 1 litre rapidly and repeat.
• Procedures: none.
• Special groups: women with kidney disease or heart disease receive fluids in 250 mL boluses with reassessment after each.
• Red flags: systolic blood pressure below 90 mmHg, pulse above 110 per minute, no urine for 8 hours, confusion, persistent vomiting, fever above 38 degrees Celsius.
• Follow-up: review in 24 to 48 hours; repeat electrolytes if abnormal; weight at each visit; antenatal care.