Pregnancy Warning Signs & Complications

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Content reviewed against published ACOG, WHO guidelines

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Most pregnancies are healthy, but knowing the warning signs of complications helps you act quickly when it matters. This page covers when to call your doctor and when to go to the emergency room.

Key takeaways

  • Call 911 or go to the ER for heavy bleeding, seizures, chest pain, or thoughts of self-harm
  • Call your provider for fever over 100.4 degrees F, persistent headache with vision changes, or decreased fetal movement
  • Preeclampsia affects 5-8% of pregnancies — regular prenatal visits detect it early
  • Gestational diabetes is treatable and manageable with diet, exercise, and sometimes medication
  • Preterm labor (before 37 weeks) may be stopped or delayed with treatment if caught early
  • Trust your instincts — if something feels wrong, call your provider

Emergency warning signs (call 911 or go to ER)

  • Heavy vaginal bleeding (soaking a pad in an hour or less)
  • Seizures or loss of consciousness
  • Chest pain or difficulty breathing
  • Severe allergic reaction
  • Trauma to abdomen (fall, car accident)
  • Thoughts of harming yourself or others
  • Prolapsed umbilical cord (cord visible or felt in vagina)

Warning signs to call your provider today

  • Fever above 100.4 degrees F (38 degrees C)
  • Severe or persistent headache with vision changes
  • Sudden swelling of face, hands, or feet
  • Decreased or absent fetal movement after 28 weeks
  • Regular contractions before 37 weeks
  • Fluid leaking from vagina (possible ruptured membranes)
  • Persistent vomiting (cannot keep fluids down)
  • Pain or burning with urination (UTI can cause preterm labor)
  • Upper abdominal pain, especially right side
  • Calf pain, swelling, or redness (possible blood clot)

Preeclampsia

Preeclampsia is a serious condition involving high blood pressure and organ damage, typically developing after 20 weeks. It affects 5-8% of pregnancies.

  • Risk factors: First pregnancy, age over 35, obesity, chronic hypertension, diabetes, multiple pregnancy, family history
  • Symptoms: Severe headache, vision changes, upper abdominal pain, sudden swelling, nausea/vomiting, shortness of breath
  • Detection: Blood pressure and urine protein checks at every prenatal visit
  • Treatment: Close monitoring, blood pressure medication, early delivery if severe
  • Prevention: ACOG recommends low-dose aspirin (81 mg) starting at 12-16 weeks for those at high risk

HELLP syndrome is a severe form of preeclampsia involving liver and blood platelet problems. It requires immediate medical attention.

Gestational diabetes

Gestational diabetes develops during pregnancy when your body cannot make enough insulin to handle increased blood sugar. It affects 2-10% of pregnancies.

  • Screening: Glucose challenge test at 24-28 weeks (earlier if high risk)
  • Risk factors: Overweight, age over 25, family history of diabetes, previous GD, polycystic ovary syndrome
  • Management: Diet modifications, regular exercise, blood sugar monitoring, and sometimes insulin or oral medication
  • Risks if untreated: Macrosomia (large baby), birth complications, newborn low blood sugar, increased C-section risk
  • After delivery: Usually resolves, but increases future type 2 diabetes risk. Get tested 6-12 weeks postpartum.

Preterm labor

Preterm labor is regular contractions that cause cervical changes before 37 weeks. About 10% of births are preterm.

  • Signs: Regular contractions (more than 4-6 per hour), pelvic pressure, low back pain, change in discharge, water breaking
  • Risk factors: Previous preterm birth, short cervix, multiple pregnancy, infections, smoking, substance use
  • Treatment: Tocolytics (medications to slow contractions), steroids to mature baby's lungs, magnesium sulfate for neuroprotection
  • Prevention: Progesterone supplementation for those with history of preterm birth or short cervix

Placental complications

  • Placenta previa: Placenta covers the cervix. Causes painless bleeding, usually detected on ultrasound. May resolve on its own. Cesarean delivery if it persists.
  • Placental abruption: Placenta separates from the uterine wall before delivery. Causes vaginal bleeding, abdominal pain, contractions, and back pain. Medical emergency requiring immediate evaluation.
  • Placenta accreta: Placenta grows too deeply into the uterine wall. Detected on ultrasound. Requires careful surgical planning for delivery.

Reducing your risk

  • Attend all prenatal appointments — many complications are caught through routine monitoring
  • Report any unusual symptoms promptly
  • Manage chronic conditions (diabetes, hypertension) before and during pregnancy
  • Maintain a healthy weight and stay physically active
  • Avoid smoking, alcohol, and recreational drugs
  • Take prescribed supplements (folic acid, prenatal vitamin)
  • Manage stress and get adequate rest

Frequently asked questions

What are the most common pregnancy complications?
The most common complications include gestational diabetes (2-10% of pregnancies), preeclampsia (5-8%), preterm labor (about 10%), and placenta previa (about 1 in 200). Many are manageable with early detection and proper monitoring.
Is spotting in early pregnancy normal?
Light spotting in the first trimester is common and often not concerning — it may be implantation bleeding or cervical sensitivity. However, heavy bleeding, bleeding with pain, or bleeding that fills a pad should be evaluated immediately. Always report bleeding to your provider.
What does preeclampsia feel like?
Preeclampsia may cause severe headaches that do not improve, vision changes (blurring, spots, light sensitivity), upper abdominal pain (especially right side), sudden swelling of face and hands, and nausea/vomiting after mid-pregnancy. Some people have elevated blood pressure with no symptoms, which is why regular prenatal visits are important.
How do I know if I am having preterm labor?
Signs include regular contractions before 37 weeks (more than 4-6 per hour), pelvic pressure, low back pain (especially if rhythmic), change in vaginal discharge, or water breaking. If you suspect preterm labor, call your provider immediately — treatment can sometimes delay delivery.
When is decreased fetal movement an emergency?
After 28 weeks, you should feel regular movement patterns. If you notice a significant decrease or absence of movement, do a kick count (you should feel 10 movements within 2 hours while resting). If you do not reach 10 movements, or if movement patterns change significantly, call your provider immediately.

Bottom line

Most pregnancies are healthy. But knowing warning signs means you can act quickly if something is wrong. Do not worry about bothering your provider — they would always rather hear from you than have you wait. When in doubt, call.

Learning about complications can feel scary. Remember: awareness is empowerment, not a prediction. Most of these conditions are treatable, especially when caught early through regular prenatal care.

All content follows our editorial policy and is reviewed against published clinical guidelines.

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