Yes, progesterone can be taken during pregnancy, and it is routinely prescribed for several specific situations. Your body already produces progesterone naturally throughout pregnancy, so supplemental progesterone isn’t introducing a foreign substance. It’s adding more of a hormone your body needs to maintain the pregnancy. That said, it’s not something every pregnant person needs, and the benefit depends heavily on your specific circumstances.
Why Progesterone Matters in Pregnancy
Progesterone is produced first by the ovaries and later by the placenta. It plays several roles that keep a pregnancy going: it prepares and maintains the uterine lining so the embryo can implant, it reduces uterine contractions that could disrupt the pregnancy, it modulates the immune system so the body doesn’t reject the embryo, and it improves blood flow between the uterus and placenta.
For roughly the first nine weeks of pregnancy, progesterone comes from a structure in the ovary called the corpus luteum. After that, the placenta gradually takes over production in what’s known as the “luteal-placental shift.” Once that transition is complete, your body no longer depends on the ovaries for progesterone. This timeline is important because it determines how long supplemental progesterone is typically needed.
When Progesterone Is Prescribed
IVF and Frozen Embryo Transfers
If you conceived through IVF, progesterone supplementation is standard. In a frozen embryo transfer cycle, hormone medications suppress your natural ovulation, which means no corpus luteum forms to produce progesterone on its own. Without supplementation, the uterine lining wouldn’t be able to support implantation. Progesterone is started several days before the embryo transfer and continued until the placenta takes over, typically around 9 to 12 weeks of gestation. It’s most commonly given as vaginal suppositories, though intramuscular injections are also used.
Threatened Miscarriage With a History of Loss
If you’re experiencing vaginal bleeding in early pregnancy and have a history of previous miscarriages, progesterone may improve your chances of a live birth. A large trial published in the New England Journal of Medicine (the PRISM trial) tested vaginal progesterone against a placebo in over 4,000 women with early pregnancy bleeding. For the overall group, progesterone didn’t produce a statistically significant benefit: 75% of women in the progesterone group had live births versus 72% in the placebo group.
But the picture changes for women with repeated losses. Current UK clinical guidelines, updated in late 2024, recommend progesterone for women with bleeding who have had two or more previous miscarriages. The numbers break down like this: women with bleeding and two prior miscarriages see roughly a 5% improvement in live birth rates, while women with three or more prior miscarriages see about a 15% improvement. That’s a meaningful difference for a low-risk treatment. The typical protocol is 400 mg of vaginal micronized progesterone twice daily, continued until 16 weeks of gestation.
Short Cervix and Preterm Birth Prevention
A cervix that measures 15 mm or shorter on ultrasound (measured between 20 and 25 weeks) puts you at significantly higher risk for early preterm delivery. A trial published in the New England Journal of Medicine found that vaginal progesterone nearly cut that risk in half: 19.2% of women on progesterone delivered before 34 weeks, compared to 34.4% on placebo. Only about 1.7% of pregnant women have a cervix this short, so this applies to a small but high-risk group. Your provider would identify this through a routine or targeted transvaginal ultrasound during the second trimester.
How It’s Taken
Progesterone in pregnancy comes in three main forms, and the one you’re prescribed depends on the reason you’re taking it.
- Vaginal suppositories or gel: The most common route for both IVF support and preterm birth prevention. Vaginal administration delivers progesterone directly to the uterus, which means lower doses can be effective with fewer whole-body side effects.
- Intramuscular injections: Used in some IVF protocols. These are oil-based injections given in the buttock, typically daily. They can cause soreness and lumps at the injection site.
- Oral tablets: Sometimes prescribed for threatened miscarriage or recurrent pregnancy loss. Oral progesterone is convenient but is metabolized by the liver before reaching the uterus, so it may be less targeted than vaginal forms.
When You Typically Stop
The stopping point depends on why you started. For IVF pregnancies, many providers continue progesterone until around 9 to 10 weeks, when the placenta has reliably taken over hormone production. Some clinics extend it to 12 weeks as a precaution. Research on IVF patients suggests that stopping at the point of a confirmed positive pregnancy test (around 4 to 5 weeks) doesn’t necessarily harm outcomes in certain groups, but most protocols err on the side of continuing longer.
For threatened miscarriage with a history of loss, guidelines recommend continuing until 16 weeks, though some women choose to stop at 12 weeks. For short cervix, treatment typically continues through the period of highest preterm birth risk, often into the third trimester. Your provider will give you a specific timeline based on your situation.
Safety for You and the Baby
Progesterone supplementation during pregnancy has a reassuring safety profile. Every pregnancy carries a baseline 3 to 5% chance of birth defects regardless of any medication, and most studies have not found that progesterone increases that risk. Some older research raised a concern about a slightly higher rate of a penile birth defect called hypospadias in boys exposed to certain synthetic progestins, but those studies had methodological problems and the findings have not been confirmed.
Studies following children up to age 5 whose mothers took progesterone during pregnancy have found no problems with brain development or other long-term outcomes. Common side effects for you are mild: drowsiness (especially with oral forms), bloating, breast tenderness, and vaginal discharge or irritation with suppositories. Injection-site soreness is the main complaint with intramuscular progesterone.
If You Haven’t Been Prescribed It
Progesterone is not beneficial for every pregnancy. If you’re having a straightforward pregnancy without bleeding, without a history of recurrent miscarriage, without a short cervix, and without IVF, there’s no evidence that taking progesterone improves outcomes. Your body is already making what it needs. Supplemental progesterone works by filling a specific gap, whether that’s a missing corpus luteum after IVF, an insufficient hormonal signal in recurrent loss, or a cervical issue that responds to the muscle-relaxing effects of the hormone. Without one of those gaps, there’s nothing for it to fix.