Pregnancy is, for most people, a healthy and uncomplicated experience. But it is also a period of significant physiological change — and some of those changes carry risk. Knowing what serious pregnancy complications look like, what causes them, and when to seek help is not frightening. It is responsible.
This is not a list designed to alarm you. It is a list designed to inform you — because the complications that cause the most harm are often the ones that go unrecognized until they have progressed further than they needed to.
Why Every Pregnant Person Should Know These
Healthcare providers screen for many of these conditions at prenatal appointments. But appointments happen every four weeks in the first and second trimester — and a lot can change in four weeks. Knowing what to watch for between appointments means you are part of your own care team, not just a passenger in your pregnancy.
The Society of Obstetricians and Gynaecologists of Canada (SOGC) publishes clinical guidelines on all of the conditions below. Your midwife or OB follows these guidelines. This guide gives you the plain-language version.
1. Preeclampsia
Preeclampsia is a condition characterized by high blood pressure and signs of organ damage — most commonly to the liver and kidneys — that develops after 20 weeks of pregnancy. It affects approximately five to eight percent of pregnancies and is one of the leading causes of maternal and fetal mortality worldwide.
Symptoms to watch for:
- High blood pressure — often discovered at a prenatal appointment before symptoms appear
- Severe headache that does not respond to pain relief
- Vision changes — blurring, flashing lights, seeing spots
- Upper right abdominal pain or shoulder pain
- Sudden swelling of the face, hands, or feet
- Nausea or vomiting after mid-pregnancy
Preeclampsia can progress rapidly. The only definitive treatment is delivery. If you experience any of the above symptoms, contact your care provider immediately — do not wait for your next scheduled appointment.
Risk factors include first pregnancy, multiple pregnancy, pre-existing high blood pressure, diabetes, kidney disease, and a personal or family history of preeclampsia.
2. Gestational Diabetes
Gestational diabetes develops when pregnancy hormones interfere with the body’s ability to use insulin effectively, causing blood sugar levels to rise above normal. It affects approximately ten to fifteen percent of pregnancies in Canada and typically develops in the second trimester.
Most women with gestational diabetes have no symptoms — which is why routine glucose screening between 24 and 28 weeks is standard prenatal care in Canada.
Unmanaged gestational diabetes increases the risk of:
- A larger-than-average baby, which can complicate delivery
- Preterm birth
- The baby having low blood sugar after birth
- Increased risk of type 2 diabetes in the mother later in life
Gestational diabetes is manageable. Most cases are controlled through diet and exercise. Some require insulin or oral medication. With proper management, outcomes are generally very good.
3. Placenta Previa
Placenta previa occurs when the placenta partially or completely covers the cervical opening. It affects approximately one in 200 pregnancies at term and is typically identified on a routine ultrasound.
The primary risk is severe bleeding — because as the cervix begins to thin and dilate in preparation for labour, a placenta covering it will bleed. This bleeding is painless, which is part of what makes it dangerous — there is no warning signal other than the bleeding itself.
Symptoms to watch for:
- Painless bright red vaginal bleeding, particularly in the second or third trimester
Women diagnosed with placenta previa are advised to avoid sexual intercourse, pelvic exams, and strenuous activity, and to deliver by cesarean section. Many cases of low-lying placenta identified in the second trimester resolve on their own as the uterus grows — your care provider will monitor this with follow-up ultrasounds.
4. Placental Abruption
Placental abruption occurs when the placenta separates from the uterine wall before delivery. It is less common than placenta previa — affecting roughly one in 100 pregnancies — but it is a medical emergency when it occurs.
Symptoms to watch for:
- Sudden, severe abdominal pain
- Back pain
- Uterine tenderness or rigidity
- Vaginal bleeding — though bleeding can be concealed behind the placenta and not always visible
Risk factors include trauma to the abdomen, cocaine use, smoking, high blood pressure, previous abruption, and rapid loss of amniotic fluid.
Partial abruptions may be managed with close monitoring. Complete abruptions require immediate delivery. If you experience sudden severe abdominal pain at any point in pregnancy, go to the emergency department. Do not wait.
5. Preterm Labour
Preterm labour is labour that begins before 37 weeks of pregnancy. Babies born prematurely face varying levels of risk depending on gestational age — babies born before 28 weeks require intensive neonatal care, while those born between 34 and 37 weeks typically do very well with appropriate support.
Symptoms to watch for:
- Regular contractions before 37 weeks — even if they are not painful
- Low, dull backache that comes and goes
- Pelvic pressure — a feeling of the baby pushing down
- Change in vaginal discharge — increased volume, or a change in colour or consistency
- Fluid leaking from the vagina
If you experience any of these symptoms before 37 weeks, contact your care provider or go to the hospital. Preterm labour is not always preventable, but early intervention can sometimes slow or stop it — and if delivery cannot be prevented, having time to administer corticosteroids to accelerate fetal lung development significantly improves outcomes.
6. Ectopic Pregnancy
An ectopic pregnancy occurs when a fertilized egg implants outside the uterus — most commonly in a fallopian tube. It cannot result in a viable pregnancy and, if untreated, can cause the tube to rupture, resulting in life-threatening internal bleeding.
Ectopic pregnancy typically becomes symptomatic between six and ten weeks. It is the leading cause of pregnancy-related maternal death in the first trimester.
Symptoms to watch for:
- Sharp or stabbing pain on one side of the abdomen or pelvis
- Vaginal bleeding or spotting
- Shoulder pain — caused by internal bleeding irritating the diaphragm
- Dizziness or fainting
If you have a positive pregnancy test and experience one-sided abdominal pain or shoulder pain, seek emergency care immediately. Ectopic pregnancy is diagnosed by ultrasound and treated either medically or surgically.
7. Hyperemesis Gravidarum
Hyperemesis gravidarum is severe, persistent nausea and vomiting during pregnancy that goes far beyond typical morning sickness. It affects approximately one to three percent of pregnancies and can result in significant weight loss, dehydration, and nutritional deficiencies that affect both mother and baby.
Signs it has gone beyond normal morning sickness:
- Vomiting more than three to four times per day
- Inability to keep any food or liquid down
- Weight loss of five percent or more of pre-pregnancy body weight
- Dark urine or inability to urinate — signs of dehydration
- Extreme fatigue and weakness
Hyperemesis gravidarum is not a mindset issue. It is not managed by eating crackers. It requires medical treatment — which may include IV fluids, anti-nausea medications, and in severe cases, hospitalization.
If you are struggling to keep food and water down and losing weight, speak to your care provider. You do not have to push through this alone.
8. Deep Vein Thrombosis and Pulmonary Embolism
Pregnancy increases the risk of blood clots because of changes in clotting factors designed to protect against excessive bleeding during delivery. Deep vein thrombosis (DVT) — a blood clot most commonly in the leg — and pulmonary embolism (PE) — a clot that travels to the lungs — are serious complications that can be life-threatening if unrecognized.
Symptoms of DVT to watch for:
- Swelling, pain, warmth, or redness in one leg — typically the calf
Symptoms of PE to watch for:
- Sudden shortness of breath
- Chest pain, particularly when breathing in
- Rapid heart rate
- Coughing up blood
Risk factors include prolonged immobility, previous DVT, obesity, multiple pregnancy, and cesarean delivery. Long-haul travel during pregnancy warrants particular attention — move regularly, stay hydrated, and discuss compression stockings with your care provider.
Any sudden shortness of breath or chest pain during pregnancy requires immediate emergency evaluation. Do not wait.
9. Intrahepatic Cholestasis of Pregnancy
Intrahepatic cholestasis of pregnancy (ICP) is a liver condition that causes intense itching — typically on the palms of the hands and soles of the feet — without a rash. It develops in the second or third trimester and is caused by a buildup of bile acids in the bloodstream.
ICP is significant because elevated bile acid levels increase the risk of stillbirth, preterm birth, and fetal distress. The itching is often dismissed as a normal pregnancy symptom — which is why it is important to know that intense itching, particularly at night and particularly on the hands and feet, warrants investigation.
Symptoms to watch for:
- Intense itching, especially on palms and soles, worse at night
- Dark urine
- Pale stools
- Jaundice in severe cases
ICP is diagnosed with a blood test measuring bile acid levels. It is managed with medication and close monitoring, and most care providers recommend early delivery — typically between 36 and 37 weeks — to reduce the risk of stillbirth.
If you are experiencing intense itching that is disrupting your sleep, mention it to your care provider at your next appointment — or call and ask about it before then.
10. Stillbirth
Stillbirth — the loss of a baby after 20 weeks of pregnancy — is the complication that is hardest to name and most important to acknowledge. It affects approximately one in 300 pregnancies in Canada. It is not rare. It is not always preventable. And it is almost never talked about in the way it deserves to be.
The most important thing every pregnant person can do is monitor fetal movement. A significant decrease in your baby’s usual pattern of movement is a warning sign that warrants immediate attention — not a wait-and-see approach.
Health Canada and the Public Health Agency of Canada advise pregnant people to contact their care provider immediately if they notice a significant change in fetal movement.
What to do:
- Know your baby’s normal pattern of movement from around 28 weeks onward
- If movement seems reduced or different from usual, drink cold water, lie on your left side, and count movements for two hours
- If you count fewer than six movements in two hours, or if something simply feels different, call your midwife, OB, or go to the hospital
You will never be told you called too soon. Trust your instincts about your own baby.
When to Go to the Emergency Department
For any of the following, do not call ahead or wait for an appointment — go directly to the emergency department or call 911:
- Sudden severe abdominal pain
- Heavy vaginal bleeding
- Sudden shortness of breath or chest pain
- Signs of a severe headache with vision changes
- Significant decrease or absence of fetal movement
- Dizziness, fainting, or shoulder pain with a known or suspected pregnancy
Your instincts about your own body are valid. If something feels wrong, seek care. The cost of being wrong is a reassuring conversation. The cost of waiting is potentially much higher.
Knowing these complications and their warning signs is one part of a prepared pregnancy. Building out your physical and practical support for the months ahead is another. Our Labour and Delivery Bag guide helps you prepare for birth day itself, and our What Not to Eat During Pregnancy guide covers the nutritional side of a safe pregnancy.
→ Read our Labour and Delivery Bag guide — everything to pack for birth day, including what Canadian hospitals provide.
→ Read our What Not to Eat During Pregnancy guide — the foods to avoid and why, for Canadian moms.
→ Shop the Cradle Song Co collection — curated essentials for pregnancy, postpartum, and baby’s first year.
