Condition guides
Pregnancy conditions, explained clearly
Clear, obgyn-reviewed guides to the conditions that can come up in pregnancy, from the common and manageable to the ones that need same-day care. Each explains what is happening, the risks to you and your baby, how it is diagnosed and treated, and exactly when to call.
Early pregnancy
Pregnancy loss & early
The first weeks, from unexpected loss to abnormal early pregnancies. Most are nobody's fault, and care protects your health and future fertility.
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Blighted Ovum
With a blighted ovum, the pregnancy sac forms and hormones rise, so a test reads positive and you feel pregnant, but no embryo ever grows inside.
How common: About half of early miscarriages
- Routine
Chemical pregnancy
A positive test, a rush of hope, then bleeding within days, close to when a period was due.
How common: Very common
- Emergency
Ectopic pregnancy
An ectopic pregnancy has implanted outside the uterus, almost always inside a fallopian tube, which is a space that cannot stretch to hold it.
How common: About 1 in 50 pregnancies
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Miscarriage
If you are reading this in the middle of it, start here: a miscarriage is almost never caused by anything you did.
How common: 10% to 20% of known pregnancies
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Missed miscarriage
There is often no bleeding, no cramping, no sign at all.
How common: A form of early miscarriage
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Molar pregnancy
A molar pregnancy happens when an error at fertilization sends the tissue that should form the placenta growing abnormally instead.
How common: About 1 in 1,000 pregnancies
- Routine
Recurrent pregnancy loss
Losing a pregnancy is hard; losing more than one can feel like your body is working against you, and it is natural to wonder whether you will ever…
How common: About 2 in 100 experience it
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Subchorionic hemorrhage
If a scan turned up a subchorionic hemorrhage, it means a small pocket of blood has collected between the pregnancy's outer membrane and the uterin…
How common: A common finding
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Threatened Miscarriage
The word threatened lands like a verdict, but it is only a warning.
How common: Bleeding affects ~1 in 4 pregnancies
Blood pressure
Hypertensive
High-blood-pressure disorders of pregnancy. They range from closely monitored to true emergencies, which is why every blood-pressure check matters.
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Chronic hypertension in pregnancy
Chronic hypertension means high blood pressure you had before pregnancy, or that shows up before 20 weeks, not the pregnancy-specific kinds that ap…
How common: About 1% to 5% of pregnancies
- Emergency
Eclampsia
Eclampsia is the onset of seizures in someone with preeclampsia, and a life-threatening emergency at the severe end of pregnancy blood pressure dis…
How common: About 3 in 10,000
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Gestational hypertension
Gestational hypertension is new high blood pressure after 20 weeks in someone whose readings were normal before, without the urine protein or organ…
How common: About 6% of pregnancies
- Emergency
HELLP syndrome
HELLP syndrome is a severe, fast-moving complication of pregnancy, usually a variant of preeclampsia.
How common: About 1 to 2 in 1,000
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Preeclampsia
Preeclampsia is a serious blood pressure disorder of the second half of pregnancy, and more than high numbers on a cuff.
How common: 5% to 8% of pregnancies
Placenta & bleeding
Placental & bleeding
How and where the placenta implants, and the bleeding that can follow. Painless or painful, sudden bleeding in pregnancy is always a same-day matter.
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Placenta accreta
Normally the placenta peels away cleanly within minutes of birth.
How common: About 1 in 272 to 1 in 533
- Emergency
Placental abruption
Sudden belly pain with vaginal bleeding in the second half of pregnancy can signal a placental abruption: the placenta peeling off the uterine wall…
How common: About 1% of pregnancies
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Placenta previa
In placenta previa, the placenta lies low and covers or nearly reaches the cervix, the opening a baby passes through during a vaginal birth.
How common: About 1 in 200 at term
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Vasa Previa
Vasa previa is a rare condition in which some of the baby's blood vessels run through the membranes across or very near the cervix, stripped of the…
How common: About 1 in 2,500
Labor & after birth
Labor & postpartum
Complications around delivery and the weeks that follow, in body and in mind. Recovery is watched as closely as the birth itself.
- Emergency
Blood Clots in Pregnancy
A blood clot in a deep vein, usually in the leg, is one of pregnancy's quieter dangers.
How common: About 1 to 2 in 1,000 pregnancies
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Breech Presentation
A breech baby sits bottom-first or feet-first instead of head-first as the due date nears.
How common: 3% to 4% at term
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Cervical Insufficiency
Cervical insufficiency, sometimes called an incompetent cervix, means the cervix opens too early, usually in the second trimester, without contract…
How common: About 1 in 100
- Routine
Pelvic girdle pain
Pelvic girdle pain, once called symphysis pubis dysfunction, is aching or sharp pain in the joints of your pelvis: the pubic bone at the front and…
How common: About 1 in 5 pregnancies
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Post-term pregnancy
A pregnancy is post-term once it reaches 42 weeks, two full weeks past the due date.
How common: Roughly 1% to 3%
- Emergency
Premature rupture of membranes
Your water breaking before labor starts is premature rupture of membranes.
How common: Term ~8% to 10%
- Emergency
Preterm labor
Preterm labor begins too early, when regular contractions start to open the cervix before 37 weeks.
How common: About 1 in 10 US births
Metabolic
Metabolic/endocrine
How pregnancy shifts blood sugar and metabolism, caught on routine screening and managed to protect you and the baby.
- Routine
Anemia in Pregnancy
Pregnancy asks your body to build far more blood, and that takes a great deal of iron, more than many people have in reserve.
How common: About 1 in 4 or more
- Routine
Gestational diabetes
Gestational diabetes rarely makes you feel any different, which is why nearly everyone is screened for it between 24 and 28 weeks.
How common: About 8% of pregnancies
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Thyroid Conditions in Pregnancy
Your thyroid, a small gland in the neck, sets your body's pace, and in pregnancy it works for two: through the first trimester your baby depends en…
How common: Underactive in 2% to 3%
Nausea & liver
Nausea & GI
Severe sickness and liver conditions that go well beyond ordinary pregnancy symptoms and deserve real treatment.
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Cholestasis of pregnancy
It often starts as an itch on the palms and soles, worse at night, with nothing on the skin to explain it.
How common: About 1 to 2 in 1,000
- Routine
Constipation in pregnancy
Slower digestion, a growing uterus pressing on the bowel, and the iron in your prenatal vitamin: put them together and constipation becomes almost…
How common: A quarter to nearly half
- Routine
Heartburn in pregnancy
That burning behind the breastbone, the sour taste, the sense that dinner is coming back up: heartburn is among the most common and most miserable…
How common: Up to 80% of pregnancies
- Routine
Hemorrhoids in pregnancy
Hemorrhoids, also called piles, are swollen veins in and around the anus and lower rectum, and pregnancy makes them almost predictable.
How common: About 30% to 40%
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Hyperemesis gravidarum
This is nausea and vomiting that has crossed a line: severe, relentless, well beyond ordinary morning sickness.
How common: 0.3% to 3% of pregnancies
- Routine
Morning sickness
The nausea usually arrives around week 6, crests near week 9, and lifts for most people as the first trimester closes.
How common: About 7 in 10 pregnancies
Growth & blood
Fluid / cord / growth
How the baby grows, and how blood type can matter. Both are followed with ultrasound and simple blood tests.
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Fetal growth restriction
Fetal growth restriction means a baby is measuring smaller than expected for its age, usually because the placenta is not delivering everything it…
How common: Up to about 10%
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Fetal macrosomia
Fetal macrosomia is the term for a baby growing larger than average, generally an estimated weight over 4,000 grams, about 8 pounds 13 ounces.
How common: About 8% to 9%
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Multiple pregnancy
Carrying twins, triplets, or more is not a disease.
How common: Twins ~1 in 30 births
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Oligohydramnios
Oligohydramnios is a shortfall of amniotic fluid, less around your baby than there should be.
How common: About 4%
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Polyhydramnios
Polyhydramnios is a buildup of too much amniotic fluid, the water your baby floats in.
How common: About 1% to 2%
- Routine
Rh incompatibility
Rh incompatibility is a blood-type mismatch between an Rh-negative pregnant person and an Rh-positive baby.
How common: About 15% are Rh-negative
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Twin-to-Twin Transfusion Syndrome
Twin-twin transfusion syndrome, or TTTS, can happen only in identical twins who share a single placenta.
How common: 10% to 15%
- Emergency
Umbilical Cord Prolapse
Umbilical cord prolapse is an obstetric emergency in which the cord slips down into or through the cervix ahead of the baby, usually right after th…
How common: About 1 in 300 births
Infections
Infections
Infections screened for and managed in pregnancy to keep a newborn safe at delivery.
- Routine
Bacterial Vaginosis in Pregnancy
Bacterial vaginosis (BV) is the most common vaginal condition in people of reproductive age, and it happens when the normal balance of vaginal bact…
How common: About 6% to 19%
- Emergency
Chorioamnionitis
Chorioamnionitis is an infection of the membranes and fluid that surround your baby, and it needs treatment right away.
How common: 2% to 5% of births
- Routine
Group B strep
Group B strep (GBS) is a common bacterium that lives harmlessly in the digestive and genital tracts of about one in four pregnant people.
How common: About 1 in 4 carry it
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Listeriosis in pregnancy
Listeriosis is a foodborne infection caused by the bacterium Listeria, and it is one reason your provider hands you that list of foods to avoid.
How common: About 1 in 25,000
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TORCH infections
TORCH is a memory aid, not a single illness.
How common: Varies by infection
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Urinary Tract Infection in Pregnancy
Urinary tract infections are among the most common infections in pregnancy, which makes them both more likely and more important to treat.
How common: Up to about 8%
No conditions match.
Do not wait
When to seek care
Pregnancy symptoms overlap, and some need care within hours. Use these three levels to orient, then open the guide for the specifics. When in doubt, call, you will not be a bother.
- Emergency
- Call 911 or go in now.
- 9 conditions in this hub
- Call your provider
- Be seen the same day.
- 27 conditions in this hub
- Routine
- Screened and managed in prenatal care.
- 12 conditions in this hub
Heavy bleeding, severe belly or shoulder-tip pain, a bad headache with vision changes, a seizure, trouble breathing, or thoughts of harming yourself or your baby are emergencies, call 911. For crisis support, call or text 988.
Editorial standards and sources
Medically Reviewed · Updated
Reviewed by Dr. Grace Lin, MD, FACOG · OB-GYN
Obstetrician-gynecologist focused on reproductive and sexual health for women: pregnancy, BV, yeast, trichomoniasis and HPV/cervical screening. Our editorial guidelines →
5 Sources
Data & references
- ACOG: Pregnancy resources and practice guidancehttps://www.acog.org/womens-health/pregnancy
- CDC: Pregnancy complicationshttps://www.cdc.gov/maternal-infant-health/pregnancy-complications/
- StatPearls (NCBI Bookshelf)https://www.ncbi.nlm.nih.gov/books/NBK430685/
- MedlinePlus (NIH): Health problems in pregnancyhttps://medlineplus.gov/healthproblemsinpregnancy.html
- March of Dimes: Complications & losshttps://www.marchofdimes.org/find-support/topics/pregnancy
This page is educational information, not medical advice or a diagnosis. If you have symptoms or a concern in pregnancy, contact your obstetric provider or, for anything urgent, go to labor and delivery or call 911.