Crinone

Use Crinone exactly as prescribed.

This medication comes in gel form and is typically applied to the vagina twice a day, every day or every other day, depending on the condition being treated. 

To use Crinone:

1. Open the sealed wrapper and remove the applicator. Do not remove the twist-off cap at this time. 
2. Insert the plunger into the open end of the applicator.  Hold the applicator on each side and push the plunger into the applicator until the plunger snaps into place. You will see about 1 inch of the plunger outside of the applicator.
3. Remove the cap. Remove the cap from the tip of the applicator by twisting it counterclockwise. Do not push the plunger while you are removing the cap. This could cause some gel to come out.
4. Prepare to insert the applicator. Choose the position that is most comfortable for you. For example, lying down on your back with your knees bent.
5. Insert the applicator. After you are in a comfortable position, gently insert the rounded tip of the applicator into your vagina.
6. Push the plunger. While the applicator is inserted in your vagina, push the plunger to release the gel into your vagina.
7. Remove the applicator from your vagina and throw it away in your household trash. It is normal for a small amount of gel to be left in the applicator. You will still get the right dose of medicine.

You may see a small amount of white discharge that may look like a vaginal discharge. This discharge may be caused by gel that can remain in your vagina, even several days after use. Gel discharge from your vagina is normal, but if you are concerned, talk to your healthcare provider.

If you miss a dose, take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and take your next dose at the regular time. Do not take two doses of Crinone at the same time.

Talk to your healthcare provider about whether it is safe to use other vaginal medicines when you are using Crinone.

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The dose your doctor recommends may be based on the following:

• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• your weight
• your age

The recommended dose of Crinone 8% for use in fertility treatments is 90 mg administered vaginally once daily in women who require progesterone supplementation. Crinone 8% is administered vaginally at a dose of 90 mg twice daily in women with partial or complete ovarian failure who require progesterone replacement. If pregnancy occurs, treatment may be continued for up to 10 or 12 weeks.

The recommended dose of Crinone 4% for use in the treatment of secondary amenorrhea is 45 mg administered vaginally every other day up to a total of six doses. For women who fail to respond, a trial of Crinone 8% 90 mg every other day up to a total of six doses may be prescribed.

• Store at 20-25ºC (68-77ºF)
• Keep out of reach of children

Progesterone is a female hormone important for ovulation and menstruation. Progesterone causes changes in the lining of your uterus, making it easier for a fertilized egg to attach to the uterus at the beginning of pregnancy. Progesterone then helps your body maintain the pregnancy.

Progesterone vaginal (for use in the vagina) is used to cause menstrual periods in women who have not yet reached menopause but are not having periods due to a lack of progesterone in the body.

Progesterone vaginal is also used in fertility treatment as part of Assisted Reproductive Technology (ART) for women unable to get pregnant due to a lack of natural progesterone in the body.

Progesterone vaginal is also used to prevent overgrowth in the lining of the uterus in postmenopausal women who are receiving estrogen hormone replacement therapy.

Progesterone vaginal may also be used for purposes not listed in this medication guide.

An overdose of progesterone vaginal is not expected to be dangerous. Seek emergency medical attention or call the Poison Help line at 1-800-222-1222 if anyone has accidentally swallowed the medication.

Along with their needed effects, progestins used in high doses sometimes cause some unwanted effects such as blood clots, heart attacks, and strokes, or problems of the liver and eyes. Although these effects are rare, some of them can be very serious and cause death. It is not clear if these problems are due to the progestin. They may be caused by the disease or condition for which progestins are being used.

The following side effects may be caused by blood clots. Although not all of these side effects may occur, if they do occur they need immediate medical attention.

Get emergency help immediately if any of the following side effects occur:

• Symptoms of blood clotting problems, usually severe or sudden, such as:
• headache or migraine
• loss of or change in speech, coordination, or vision
• numbness of or pain in chest, arm, or leg
• unexplained shortness of breath

Check with your doctor as soon as possible if any of the following side effects occur:

• Changes in vaginal bleeding (increased amounts of menstrual bleeding occurring at regular monthly periods, lighter vaginal bleeding between menstrual periods, heavier vaginal bleeding between regular monthly periods, or stopping of menstrual periods)
• symptoms of blood sugar problems (dry mouth, frequent urination, loss of appetite, or unusual thirst)

• Mental depression
• skin rash
• unexpected or increased flow of breast milk

• Backache
• dizziness
• filling or rounding out of the face
• irritability
• mental depression
• nausea or vomiting
• unusual decrease in sexual desire or ability in men
• unusual tiredness or weakness

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Abdominal pain or cramping
• bloating or swelling of ankles or feet
• blood pressure increase (mild)
• dizziness
• drowsiness (progesterone only)
• headache (mild)
• mood changes
• nervousness
• pain or irritation at place of injection site
• swelling of face, ankles, or feet
• unusual or rapid weight gain

• Acne
• breast pain or tenderness
• brown spots on exposed skin, possibly long-lasting
• hot flashes
• loss or gain of body, facial, or scalp hair
• loss of sexual desire
• trouble in sleeping

Not all of the side effects listed above have been reported for each of these medicines, but they have been reported for at least one of them. All of the progestins are similar, so any of the above side effects may occur with any of these medicines.

After you stop using this medicine, your body may need time to adjust. The length of time this takes depends on the amount of medicine you were using and how long you used it. During this period of time check with your doctor if you notice the following side effect:

• Dizziness
• nausea or vomiting
• unusual tiredness or weakness

• Delayed return to fertility
• stopping of menstrual periods
• unusual menstrual bleeding (continuing)

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Use this medicine as ordered by your doctor. Read all information given to you. Follow all instructions closely.

• Follow how to use as you have been told by the doctor or read the package insert.
• Do not take Crinone by mouth. For vaginal use only. Keep out of your mouth, nose, and eyes (may burn).
• Wash hands before and after use.
• Do not use the applicators more than 1 time.
• Do not take other vaginal drugs within 6 hours of this medicine.

What do I do if I miss a dose?

• Take a missed dose as soon as you think about it.
• If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
• Do not take 2 doses at the same time or extra doses.

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
• Chest pain or pressure.
• Shortness of breath.
• Coughing up blood.
• Weakness on 1 side of the body, trouble speaking or thinking, change in balance, drooping on one side of the face, or blurred eyesight.
• Swelling, warmth, numbness, change of color, or pain in a leg or arm.
• Shortness of breath, a big weight gain, or swelling in the arms or legs.
• Trouble walking.
• Very bad headache.
• Very upset stomach or throwing up.
• Very bad dizziness or passing out.
• Bulging eyes.
• Change in eyesight.
• Loss of eyesight.
• A lump in the breast, breast soreness, or nipple discharge.
• Breast pain.
• Vaginal itching or discharge.
• Vaginal bleeding that is not normal.
• Pain when passing urine.
• Passing urine more often.
• Low mood (depression).
• Mood changes.
• Memory problems or loss.
• Seizures.
• Flushing.
• A fast heartbeat.
• A heartbeat that does not feel normal.

Assisted Reproductive Technology

Crinone 8% is administered vaginally at a dose of 90 mg once daily in women who require progesterone supplementation. Crinone 8% is administered vaginally at a dose of 90 mg twice daily in women with partial or complete ovarian failure who require progesterone replacement. If pregnancy occurs, treatment may be continued until placental autonomy is achieved, up to 10 to 12 weeks.

Secondary Amenorrhea

Crinone 4% is administered vaginally every other day up to a total of six doses. For women who fail to respond, a trial of Crinone 8% every other day up to a total of six doses may be instituted.

It is important to note that a dosage increase from the 4% gel can only be accomplished by using the 8% gel. Increasing the volume of gel administered does not increase the amount of progesterone absorbed.

Crinone® 4% and Crinone® 8%
(progesterone gel)
For Vaginal Use Only

Please read this information carefully before you start to use Crinone and each time your prescription is renewed, in case anything has changed. This leaflet does not take the place of discussions with your doctor. If you still have any questions, ask your doctor or healthcare provider.

What is Crinone?

Crinone is medicine that contains the female hormone called progesterone.

What is Crinone used for?

• Crinone 4% and Crinone 8% are used to treat the absence of a menstrual period in a woman who has previously had a menstrual period. Progesterone is one of the hormones that allows women to have regular menstrual periods. When you do not produce enough progesterone, menstrual irregularities can occur. Crinone may be prescribed to increase your progesterone.
• Crinone 8% is also used as part of a program for women who are undergoing fertility treatments to get pregnant. Progesterone is one of the hormones that helps to prepare the lining of your uterus so that it is ready to receive and nourish a fertilized egg and to continue a pregnancy. If you are undergoing ART treatment and your doctor has determined your body does not produce enough progesterone on its own, Crinone may be prescribed to increase your progesterone.
• If pregnancy occurs, Crinone may be supplemented for 10 to 12 weeks until production of progesterone by the placenta is adequate.

Who should not use Crinone?
Do not start using Crinone if you:

• Are allergic to progesterone, progesterone-like drugs, or any of the inactive ingredients in the gel (ask a pharmacist if you are not sure about the inactive ingredients in Crinone).
• Have unusual vaginal bleeding which has not been evaluated by a doctor.
• Have or have had a liver disease.
• Have or have had cancer of the breast or genital organs.
• Have had a miscarriage and your physician suspects some tissue is still in the uterus.
• Have or have had blood clots in the legs, lungs, eyes, or elsewhere.

What are the possible side effects of Crinone?
Serious side effects include:

• Blood clots. Progestational drug products may increase your chance of having blood clots in your blood vessels. Blood clots can cause:
  • blood vessel problems (thrombophlebitis)
  • stroke
  • loss of your arm or leg
  • blood clot in your lungs (pulmonary embolus)
  • heart attack
  • death
• Birth defects. Abdominal wall defect and cleft palate have been reported with Crinone use in early pregnancy. It is not known if these defects were caused by Crinone.

Call your healthcare provider right away if you get any of the following warning signs or any other unusual symptoms that concern you:

• Pains in the calves or chest, a sudden shortness of breath or coughing blood indicating possible clots in the legs, heart, or lungs.
• Severe headache or vomiting, dizziness, faintness, or changes in vision or speech, weakness or numbness of an arm or leg indicating possible clots in the brain or eye.

Common side effects include:

• abdominal pain
• perineal pain (the perineum is the area between the vagina and the rectum)
• cramps
• bloating
• headache
• fatigue
• increased appetite
• contstipation
• diarrhea
• nausea
• joint pain
• depression
• mood swings
• sleep disorder
• nervousness
• decreased libido
• breast enlargement
• excessive urination at night
• vaginal discharge
• upper respiratory tract infection

These are not all the possible side effects of Crinone. For more information, ask your healthcare provider or pharmacist for advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

How should I use Crinone?

Use as directed by your healthcare provider.

Read the Instructions for Use included in this leaflet for information on the right way to use Crinone.

Additional information about Crinone

• You may see a small amount of white discharge that may look like a vaginal discharge. This discharge may be caused by gel that can remain in your vagina, even several days after use. Gel discharge from your vagina is normal, but if you are concerned, talk to your healthcare provider.
• If you miss a dose of Crinone, use it as soon as you remember.
• Do not use more Crinone than the dose prescribed by your doctor.
• Talk to your healthcare provider about whether to use other vaginal medicines when you are using Crinone.

General information about the safe and effective use of Crinone

Medicines are sometimes prescribed for purposes other than those listed in a Patient Information Leaflet. Do not use Crinone for another condition. Your doctor has prescribed this drug for you and you alone. Do not give this drug to anyone else, even if they have the same condition.

Keep Crinone out of the reach of children

This leaflet provides the most important information about Crinone. If you would like more information, talk with your healthcare provider or pharmacist. You can ask for information about Crinone that is written for health professionals.

You can get more information by calling the toll free number 1-888-776-4358 or visit www.Crinoneusa.com.

What are the ingredients in Crinone?

Crinone contains either 45 mg (4% gel) or 90 mg (8% gel) of progesterone in a base containing glycerin, light mineral oil, polycarbophil, carbomer homopolymer Type B, hydrogenated palm oil glyceride, sorbic acid, purified water and may contain sodium hydroxide.

How should I store Crinone?

Store Crinone at room temperature between 68°F to 77°F (20°C to 25°C).
Do not use Crinone after the expiration date printed on the box.

INSTRUCTIONS FOR USE
Crinone® 4% and Crinone® 8% ("KRI-noan")
(progesterone gel)

For Vaginal Use Only

You will need the following supplies: See Figure A.

Step 1.  Remove the applicator from the sealed wrapper.

• Open the sealed wrapper and remove the applicator. Do not remove the twist-off cap at this time. See Figure B.
  

Step 2. Insert the plunger into the open end of the applicator. See Figure C. 

• Hold the applicator on each side and push the plunger into the applicator until the plunger snaps into place.
• You will see about 1 inch of the plunger outside of the applicator.

Step 3. Remove the cap. See Figures D and E.

• Remove the cap from the tip of the applicator by twisting it counterclockwise. 
• Do not push the plunger while you are removing the cap. This could cause some gel to come out.

Step 4. Prepare to insert the applicator. See Figure F.

Choose the position that is most comfortable for you. For example, lying down on your back with your knees bent.

Step 5. Insert the applicator. See Figure G.

• After you are in a comfortable position, gently insert the rounded tip of the applicator into your vagina.

Step 6. Push the plunger. See Figure H.

• While the applicator is inserted in your vagina, push the plunger to release the gel into your vagina.

Step 7. Remove the applicator from your vagina and throw it away in your household trash.

• It is normal for a small amount of gel to be left in the applicator. You will still get the right dose of medicine.

This Instructions for Use has been approved by the U.S. Food and Drug Administration.

Rx only

For all medical inquiries contact:
ACTAVIS
Medical Communications
Parsippany, NJ 07054
1-800-272-5525

Distributed By:
Actavis Pharma, Inc.
Parsippany, NJ 07054 USA

Content Updated: August 2014

202084-01

Common side effects of Crinone include: depression. See below for a comprehensive list of adverse effects.

Summary of Use during Lactation

Release from the progesterone-releasing intrauterine device available in the United States is 65 mcg/day or only 0.65% of the dose released from most of the devices reported in the literature. Because of the low levels of progesterone in breastmilk, even with the high-dose products, amounts ingested by the infant are small and would not be expected to cause any adverse effects in breastfed infants. The progesterone vaginal ring available in some countries produces maternal blood levels that are lower than those of ovulating women.[1] Most studies indicate that progesterone is not detrimental to milk production or duration of nursing.[2][3] No special precautions appear to be required.

In Russia, a progesterone gel (Progestogel - Besins Healthcare; not available in the US) has been used topically as a one-time application to the breasts to treat postpartum breast engorgement when more conservative measures have failed.[4] A subsequent study failed to detect any decrease in breast hardness 20 minutes after application of progesterone gel in mothers with engorgement.[5] The safety and efficacy of this use have not been well studied and the manufacturer of Progestogel recommends avoiding its use during lactation.

Drug Levels

Maternal Levels. Women who received 6 subdermal implants containing 100 mg each of progesterone between days 30 to 35 postpartum for contraception had milk progesterone levels measured. Milk progesterone levels were 5.7 mcg/L in 6 women at 3 to 4 months postpartum and 6.3 mcg/L in 7 women at 9 to 12 months postpartum. By comparison, 9 women who received a Copper T intrauterine device had negligible progesterone levels. The authors estimated that infants would receive about 5 mcg of progesterone daily through breastmilk.[6][7]

Infant Levels. Women received 6 subdermal implants containing 100 mg each of progesterone between days 30 to 35 postpartum for contraception. A metabolite of progesterone, pregnane-3-glucuronide, was measured in the urine of their infants. At 3 to 4 months (n = 9) and 9 to 12 months (n = 7) postpartum, urine metabolite levels were 6.3 mcg/L and 15.7 mcg/L, respectively. These values were not significantly different from those of infants whose mothers were using a Copper T intrauterine device.[6][7]

Effects in Breastfed Infants

Eighty-four women had 6 subdermal implants containing 100 mg each of progesterone inserted between days 30 to 35 postpartum as a contraceptive. Compared to women who received either a placebo or a Copper T intrauterine device, there were no differences in the growth rates of their infants over the first 6 months postpartum.[8]

One hundred ninety-two mothers who received 6 subdermal implants containing 100 mg each of progesterone inserted on postpartum day 60 as a contraceptive. The weight gain of 60 infants who were exclusively breastfed for 6 months was compared to that of infants whose mothers received either placebo (n = 68 at day 30) or a Copper T (n = 64 at day 30 and n = 49 at day 60) intrauterine device. No differences were found in the average weight gains among the 3 groups of infants at 6 months of age.[9]

Vaginal rings that released progesterone were inserted at about 60 days postpartum in 128 women. The 2 types of rings released progesterone either 7.5 mg daily decreasing to 4.5 mg at 90 days or 15 mg daily decreasing to 7 mg daily at 90 days. Over the first 12 months postpartum, no differences in weight gain were found between the exclusively breastfed infants of mothers who received the progesterone rings and control mothers who received a Copper T intrauterine device for contraception.[10]

One hundred twenty breastfeeding women used a vaginal ring that released about 10 mg daily of progesterone for 90 days, starting during weeks 5 to 7 postpartum. No differences were found in the growth of breastfed infants or in developmental milestones compared to the normal population values.[11]

One hundred eighty-seven breastfeeding women used a vaginal ring that released about 10 mg daily of progesterone, starting at about day 57 postpartum. No differences were found in weight gain during the first 6 months of use compared to infants whose mothers received either a Copper T intrauterine device, an oral progestin-only contraceptive or levonorgestrel implant.[12]

A study comparing 100 women who received vaginal ring that released about 10 mg daily of progesterone to those who received a Copper T intrauterine device between days 29 and 64 postpartum found no differences in weight gain of their breastfed infants over the first year postpartum.[13]

Two hundred eighty-five women who received a vaginal ring that released about 10 mg daily of progesterone were compared to 262 women who received a Copper T intrauterine device beginning between weeks 5 and 9 postpartum. No differences in the weight gain of breastfed infants were seen between the 2 groups during the 14-month observation period.[14]

Effects on Lactation and Breastmilk

Eighty-four women had 6 subdermal implants containing 100 mg each of progesterone inserted between days 30 to 35 postpartum as a contraceptive. Compared to women who received either a placebo or a Copper T intrauterine device, no difference was found in the breastfeeding rates during the first 9 months postpartum. At 1 year postpartum, more women in the Copper T group were breastfeeding than in the progesterone or placebo groups.[8]

Vaginal rings that released progesterone were inserted at about 60 days postpartum in 246 women. The 3 types of rings released progesterone either 5, 10 or 15 mg daily. Control women received a Copper T intrauterine device. At 6 and 12 months postpartum there was no significant difference in the percentage of infants who were breastfed between the progesterone and Copper T groups.[15]

One hundred twenty breastfeeding women used a vaginal ring that released about 10 mg daily of progesterone, starting during weeks 5 to 7 postpartum. The rate of weaning was greater in the progesterone ring group than in groups of women who received levonorgestrel or norethindrone implants for postpartum contraception.[11]

In a multicenter study, 802 women who received a vaginal ring that released about 10 mg daily of progesterone were compared to 734 women who received a Copper T intrauterine device beginning at day 29 to 63 postpartum. No differences were found in the rate of breastfeeding between the 2 groups over the first year postpartum.[16]

Two hundred eighty-five women who received a vaginal ring that released about 10 mg daily of progesterone were compared to 262 women who received a Copper T intrauterine device beginning between weeks 5 and 9 postpartum. No differences in the breastfeeding rates were seen between the 2 groups during the 14-month observation period.[14]

An observational study followed 192 women who used a vaginal ring that released 10 mg of progesterone daily beginning between days 54 and 64 postpartum. All subjects used the vaginal ring for at least 4 months; 90% were still using it at 6 months and 73% were using it at 9 months postpartum. The duration of breastfeeding and infant growth were similar to reference groups.[17]

Alternate Drugs to Consider

(Contraception) Etonogestrel, Intrauterine Copper Contraceptive, Levonorgestrel, Oral, Levonorgestrel, Intrauterine, Medroxyprogesterone Acetate, Norethindrone

References

1. RamaRao S, Clark H, Merkatz R, Sussman H, Sitruk-Ware R. Progesterone vaginal ring: introducing a contraceptive to meet the needs of breastfeeding women. Contraception. 2013;88:591-8. PMID: 23769015

2. Carr SL, Gaffield ME, Dragoman MV, Philips S. Safety of the progesterone-releasing vaginal ring (PVR) among lactating women: A systematic review. Contraception. 2016;94:253-61. PMID: 25869631

3. Phillips SJ, Tepper NK, Kapp N et al. Progestogen-only contraceptive use among breastfeeding women: A systematic review. Contraception. 2016;94:226-52. PMID: 26410174

4. Pustotina O. Management of mastitis and breast engorgement in breastfeeding women. J Matern Fetal Neonatal Med. 2015;1-5. PMID: 26513602

5. Alekseev NP. Progesterone-containing gel does not eliminate postpartum breast engorgement? Breastfeed Med. 2017;12:122-3. PMID: 28170298

6. Croxatto HB, Diaz S et al. Subdermal progesterone implants for fertility regulation in nursing women. In, Zatuchni GI, Goldsmith A, Shelton JD, Sciara JJ, eds. Long-acting contraceptive delivery systems. Philadelphia. Harper & Row. 1984.

7. Croxatto HB, Diaz S. The place of progesterone in human contraception. J Steroid Biochem. 1987;27:991-4. PMID: 3320572

8. Croxatto HB, Diaz S et al. Fertility regulation in nursing women. II. Comparative performance of progesterone implants versus placebo and copper T. Am J Obstet Gynecol. 1982;144:201-8. PMID: 7114130

9. Diaz S, Peralta O et al. Fertility regulation in nursing women. VI. Contraceptive effectiveness of a subdermal progesterone implant. Contraception. 1984;30:311-25. PMID: 6509984

10. Diaz S, Jackanicz TM et al. Fertility regulation in nursing women: VIII. Progesterone plasma levels and contraceptive efficacy of a progesterone-releasing vaginal ring. Contraception. 1985;32:603-22. PMID: 3912105

11. Shaaban MM. Contraception with progestogens and progesterone during lactation. J Steroid Biochem Mol Biol. 1991;40:705-10. PMID: 1835650

12. Diaz S, Zepeda A et al. Fertility regulation in nursing women IX. Contraceptive performance, duration of lactation, infant gowth, and bleeding patterns during use of progesterone vaginal rings, progestin-only pills, Norplant implants, and Copper T 380-A intrauterine devices. Contraception. 1997;56:223-32. PMID: 9408703

13. Chen JH, Wu SC et al. The comparative trial of TCu 380A IUD and progesterone-releasing vaginal ring used by lactating women. Contraception. 1998;57:371-9. PMID: 9693396

14. Massai R, Miranda P et al. Preregistration study on the safety and contraceptive efficacy of a progesterone-releasing vaginal ring in Chilean nursing women. Contraception. 1999;60:9-14. PMID: 10549447

15. Croxatto HB, Diaz S. Progesterone vaginal rings for contraception during breastfeeding. In, Runnebaum R, Rabe T, Kiesel L, eds. Advances in gynecological and obstetric research series. Vol. 2. Female contraception and male fertility regulation. New Jersey. Parthenon. 1987;2:135-42.

16. Sivin I, Diaz S et al. Contraceptives for lactating women: a comparative trial of a progesterone-releasing vaginal ring and the copper T 380A IUD. Contraception. 1997;55:225-32. PMID: 9179454

17. Massai R, Quinteros E, Reyes MV et al. Extended use of a progesterone-releasing vaginal ring in nursing women: a phase II clinical trial. Contraception. 2005;72:352-7. PMID: 16246661