Recently we got a question on our GOUD Social Forum from a mom-to-be who asked when lung maturity injections should be given during pregnancy. It's a great question, and we realized it’s one, many expecting parents might have but don’t always ask. So let’s talk about it.
What Are Lung Maturity Injections?
Lung maturity injections are corticosteroid shots given to pregnant women who are at risk of delivering early. The goal is to speed up the baby’s lung development so that if the baby is born prematurely, they have a better chance of breathing on their own without needing intense support.
Doctors have been using this treatment since the early 1970s. It’s now a standard part of care for women at risk of preterm birth, and the science behind it is solid. In multiple studies, these steroids have been shown to cut the risk of serious breathing problems in premature babies by about 50%.
The two most commonly used medications are betamethasone and dexamethasone. Both cross the placenta well, don’t suppress the baby’s immune system much, and leave the baby’s bloodstream fairly quickly, within about 40 hours.
What Do These Injections Actually Do?
Let’s break it down.
These medications do two main things:
- They help the baby’s lungs produce surfactant.
- Surfactant is a substance that coats the inside of the lungs and keeps the tiny air sacs from collapsing. It usually doesn’t show up until around 32 weeks of pregnancy. Without enough of it, a baby born early can struggle to breathe or even suffer from respiratory distress syndrome.
- They help increase lung volume and reduce fluid in the baby’s lungs.
- That gives the baby a much better shot at breathing well right after birth.
When Are These Injections Given?
They’re typically given if a woman is between 24 and 34 weeks pregnant and there's a real chance she’ll go into labor soon. That could be because:
- She’s having regular, painful contractions
- Her cervix is opening too early
- Her water has broken
- She’s had a history of preterm labor
- She’s carrying twins or more
- She’s dealing with complications like infections, excess fluid, or uterine abnormalities
Sometimes the signs are subtle. Back pain, pressure in the pelvis, or unusual discharge can all be early signals that something’s off. If anything seems out of the ordinary, it’s always worth checking in with your doctor or midwife.
How Are They Given?
There are two standard options:
- Betamethasone: 12 mg via intramuscular injection, repeated once after 24 hours
- Dexamethasone: 6 mg via intramuscular injection, repeated every 12 hours for a total of 4 doses
Both are effective. Your doctor will decide which one makes more sense based on availability and your specific situation.
Do You Ever Need a Second Round?
Yes, but only under certain conditions.
If you don’t deliver within 7 days of getting the first round, and your doctor still believes there’s a high chance of preterm delivery, you might get a booster dose. But this is done with care, because too many doses can have downsides, especially if delivery keeps getting pushed further out.
Are They Always Needed?
No. If you're past 34 weeks, these injections aren’t usually recommended. By then, most babies’ lungs are developed enough, and the benefits of steroids don’t outweigh the risks.
Also, not every early labor scenario calls for lung maturity shots. Your doctor will weigh your medical history, how far along you are, and how likely early delivery seems. It’s not a one-size-fits-all decision.
Lung maturity injections are a powerful tool, but they’re used with purpose. If you’re between 24 and 34 weeks and at real risk of going into labor early, they can make a huge difference in your baby’s outcome. If you’re not at risk, or if you’re past 34 weeks, you probably don’t need them.
Talk to your doctor. Ask questions. You don’t need to memorize every detail, you just need to feel confident that your care is thoughtful, informed, and right for you and your baby. And if you're the mom who asked this on our forum, thank you. This helped more people than you know.
