Bleeding During Pregnancy: What’s Normal and What’s Not

By Dr Greg Jenkins | Sydney-based specialist in Fertility, Obstetrics and Gynaecology

One of the most common, and understandably worrying, calls I get from pregnant patients is about bleeding. Whether it’s light spotting or something heavier, bleeding at any stage of pregnancy can trigger fear that something is wrong.

The reality? Not all bleeding means there’s a problem. In fact, some spotting is fairly common, especially in the first trimester. But it’s also true that certain types of bleeding do warrant a closer look.

In this blog, I’ll walk you through what bleeding can mean at different stages of pregnancy—what’s considered normal, when to monitor and when to seek help. My goal is to help you feel more informed and less alarmed if you ever find yourself in this situation.

First Trimester: Spotting is Common—but Pay Attention to Symptoms

Early pregnancy is when I hear about bleeding most often. Many people experience light spotting in the first 12 weeks, often without any complications.

Some common causes include:

• Implantation bleeding: This can happen when the fertilised egg attaches to the uterine lining, usually around the time your period would have been due. It’s typically very light and short-lived.

• Cervical changes: Pregnancy hormones increase blood flow to the cervix, which means things like sex, a Pap smear, or even strenuous activity can cause a small amount of spotting.

• Subchorionic haematoma: A small collection of blood between the uterine wall and the sac. These are relatively common and often resolve on their own.

When to call your doctor:

If the bleeding is heavier than a period, is accompanied by pain, or you notice clots or tissue, it’s important to get checked. These could be signs of miscarriage or, more rarely, an ectopic pregnancy (when the embryo implants outside the uterus, usually in the fallopian tube). Ectopic pregnancies can be serious if not diagnosed early.

Even if symptoms are mild, it’s always okay to call for reassurance. In early pregnancy, we usually recommend a combination of blood tests and an ultrasound to get clarity.

Second Trimester: Less Common, More Cause for Review

Bleeding becomes less common in the second trimester (13 to 27 weeks), so if it does occur, we tend to look into it a little more closely.

Possible causes include:

• Placenta previa: This is when the placenta lies low in the uterus and may partially or fully cover the cervix. It can cause painless bleeding, usually in the second or third trimester.

• Cervical insufficiency: If the cervix shortens or begins to open too early, it can sometimes lead to spotting or bleeding.

• Infection or inflammation: Occasionally, infections of the cervix or vagina can cause irritation and bleeding.

When to call your doctor:

Any bleeding in the second trimester should be assessed—especially if it’s persistent, heavy or associated with discomfort or contractions. It may not always be a sign of a major problem, but it’s not something to ignore.

Third Trimester: Heavier Bleeding Can Be More Serious

In the final trimester, bleeding is less likely to be harmless and should always prompt a check-in.

Things we look out for:

• Placental abruption: This occurs when the placenta begins to detach from the uterine wall before birth. It can cause painful bleeding, abdominal tightness and reduced baby movements—and it’s an obstetric emergency.

• Labour-related changes: As your body prepares for labour, you may notice a 'bloody show'—a small amount of blood mixed with mucus. This is usually a normal sign that labour is near.

• Placenta previa (rare): A condition where the placenta is covering the cervix or close to it. This will usually have been identified by ultrasound earlier in the pregnancy and always requires review and assessment.

When to call your doctor or go to hospital:

If you’re in your third trimester and experience any bleeding, especially if it’s heavy or bright red, call immediately or head to your nearest hospital. It’s always better to be cautious at this stage of pregnancy.

The Bottom Line: Don’t Panic, But Don’t Guess

Bleeding in pregnancy can be unsettling, no matter when it happens. While there are many benign explanations, especially early on, it’s never wrong to ask for advice.

The most important thing I tell my patients is this: you don’t need to figure it out on your own. We’d always rather hear from you and reassure you than have you sitting at home wondering if something is wrong.

If you’re bleeding, take note of:

• How much blood there is

• Whether it’s light, moderate, or heavy

• The colour (bright red, brown, pink)

• Any pain or cramping

• Any other symptoms (like dizziness or reduced baby movements)

Write it down if it helps, and give us a call. Whether it turns out to be nothing or something that needs attention, we’ll walk through it together.