Preterm labor

• Preterm labor and delivery can happen to any pregnant woman.
• Women can take steps to reduce the risk of preterm labor.
• Know the signs of preterm labor and what to do about them.

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There are three kinds of drugs (medications) that you may be given if you're having preterm labor. These drugs:

• Help slow or stop labor contractions
• Help your baby's lungs mature and breathe
• Help prevent infection in you or your baby

Stopping contractions 
The medications described below help lessen or stop contractions. They're given through an intravenous (IV) tube, by mouth or rectally.

These medications may cause side effects for you, your baby, or both. The side effects for your baby may happen while you're pregnant or after you've given birth. These side effects can be upsetting, uncomfortable and, sometimes, serious. Side effects are different for every woman. Before choosing a drug, talk with your health care provider to understand and weigh the medication's risks and benefits. Your provider can help you choose a medication that's best for you and your baby.

Calcium channel blockers (nifedipine)
Some possible side effects for you include:

• Redness of the skin
• Headache
• Dizziness
• Nausea
• Low blood pressure

Possible side effects for your baby:
No side effects shown as of yet

Prostaglandin synthetase inhibitors
These include medications like indomethacin, ketorolac, sulindac. Some possible side effects for you include nausea or heartburn.

Possible side effects for your baby include:

• Tightening of the blood vessel through which your baby's blood flows from one major blood vessel to another (ductus arteriosus)
• Increasing blood pressure in the lungs
• Decreasing in kidney function
• Bleeding within the brain or heart
• Yellowing of the skin and eyes (jaundice)
• Decreasing blood flow to the bowel resulting in infection (necrotizing enterocolitis)

Magnesium sulfate
Possible side effects for you include:

• Redness of the skin
• Tiredness and drowsiness
• Headache
• Muscle weakness
• Double vision
• Dry mouth
• Fluid in the lungs
• Heart attack

Possible side effects for your baby include:

• Tiredness and drowsiness
• Decreased muscle tone
• Slowed breathing
• Loss of minerals

Beta-mimetics (terbutaline, ritodrine)
Possible side effects for you include:

• Fast heartbeat
• Fluid in the lungs
• Poor blood flow
• Low blood pressure
• High levels of sugar in the blood
• Highlevels of insulin (a kind of protein) in the blood
• Low amounts of potassium in the blood
• Less amounts of urine
• Changes in the function of the thyroid gland
• Shaking
• Nervousness
• Nausea or vomiting
• Fever
• Hallucinations

Possible side effects for your baby include:

• Fast heartbeat
• High levels of insulin in the blood
• Low or high levels of sugar in the blood
• Enlarged heart
• Poor blood flow
• Low levels of calcium in the blood
• Jaundice
• Low blood pressure
• Bleeding within the brain or heart

Helping your baby breathe
If you go into preterm labor, you'll likely get a type of steroid drug called a corticosteroid. This drug helps your baby's lungs mature so that he can breathe more easily after birth. Steroids reduce any breathing problems your baby may have and help prevent a serious lung disease called respiratory distress syndrome. Steroids also help prevent bleeding in your baby's brain and a serious bowel disease called necrotizing enterocolitis. The recommended steroid drugs are called dexamethasone and betamethasone.

Preventing infection 
If you're having preterm labor you'll be given antibiotics. These drugs help prevent infection in both you and your baby. Premature babies are at increased risk of infection because their immune systems (which help fight against infection) aren't fully developed.

June 2005 (7-09)

The information in this article is based on ACOG Practice Bulletin, number 43 (May 2003), produced by the American College of Obstetricians and Gynecologists.