Bleeding in pregnancy can cause great anxiety for expectant parents. Although a true menstrual period cannot occur, various types of bleeding may present—from benign implantation spotting through to serious issues such as ectopic pregnancy. This guide lays out the principal causes, highlights the hallmark symptoms, details recommended investigations, and offers practical advice on how to proceed.
Why You Can’t Have a Period During Pregnancy
A period arises when the thickened uterine lining sheds in the absence of fertilisation. When you’re pregnant, that lining remains intact to nourish the embryo. Any bleeding you experience while pregnant therefore stems from other mechanisms—not a menstrual cycle.
Period vs Pregnancy Bleeding: How to Tell Them Apart
Period: heavier, continuous flow over 3–7 days, recurring cyclically, often with cramps.
Pregnancy bleeding: typically light spotting, bright to dark red, lasting hours to a few days, and occurring unpredictably.
Quick Guide: Interpreting Colour, Volume & Associated Symptoms
Small distinctions can offer rapid insight:
- Light pink or brownish: often implantation or hormone-related spotting.
- Bright red spotting after intercourse or examination: contact bleeding from a sensitive cervix.
- Dark red, heavier, with tissue: may signal a threatened miscarriage— seek urgent medical assessment.
- Sudden heavy bleed with one-sided pain or dizziness: possible ectopic pregnancy or placental complication—attend A&E immediately.
Common Causes of Bleeding in Pregnancy
Implantation Spotting
Around 6–12 days post-fertilisation, the blastocyst embeds in the uterine lining, occasionally rupturing tiny vessels. This appears as very light pink or brownish spotting, rarely lasting beyond two days. Further information is available from ACOG (USA).
Hormone-Related “Breakthrough” Bleeding
Short-term hormonal fluctuations—often around your expected period date—can provoke a mild withdrawal bleed. It’s shorter and lighter than a normal period and resolves of its own accord.
Contact Bleeding
The cervix is highly vascular during pregnancy. Sexual intercourse or a vaginal examination can nick superficial vessels, causing bright red bleeding that typically ceases within a few hours.
Infections & Minor Trauma
Bacterial vaginosis, yeast infections, or minor abrasions (for example, from tampon use) can irritate the lining. A vaginal swab identifies the culprit and guides treatment. Patient information is provided by NHS (UK).
Serious Complications
Some bleeding indicates urgent pathology:
- Ectopic pregnancy: typically after six weeks, with severe one-sided pain and substantial bleeding.
- Miscarriage: cramp-like pain, increasing bleeding and passage of tissue.
- Placenta praevia or abruption: painless bright red bleeding in the second or third trimester—always an emergency.
Bleeding by Trimester: How Common Is It?
First Trimester (0–12 weeks)
Light bleeding is most prevalent in this phase—often due to implantation or hormonal shifts. Nonetheless, it should be assessed to exclude complications.
Second Trimester (13–27 weeks)
Bleeding is less common. Should it occur, clinicians will focus on placental placement and cervical length.
Third Trimester (28–40 weeks)
Any fresh bleeding is potentially serious—it may herald preterm labour or placental abruption and warrants immediate hospital evaluation.
Investigations: Which Tests Reveal What?
Healthcare professionals employ a combination of assessments to obtain swift clarity:
- Transvaginal ultrasound: visualises embryo location, heartbeat and placenta.
- Doppler scan: evaluates blood flow in the uterus and placenta.
- Laboratory investigations: serial hCG measurements, progesterone levels, full blood count (FBC) and inflammatory markers.
- Vaginal swab: detects bacterial or fungal infections (guidance from RCOG).
Self-Monitoring & First-Aid
If you notice light bleeding, follow these steps:
- Observe: record colour, volume and duration, noting any pain, fever or dizziness.
- Use sanitary pads: avoid tampons to better assess blood loss.
- Rest: refrain from strenuous activity, exercise and heavy lifting.
- Seek care promptly: attend your clinic or hospital if bleeding intensifies, you pass tissue, or you experience faintness.
Conclusion
Bleeding during pregnancy can be distressing, but is often harmless. Since a genuine period cannot occur, any bleeding should be evaluated without delay to rule out serious causes and safeguard both you and your baby.