Pregnancy Complications & Warning Signs
Most pregnancies are uncomplicated — but knowing which symptoms require urgent action, and which are simply part of the process, is one of the most genuinely important things you can learn.
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Before anything else: if something feels wrong, contact your midwife or maternity triage unit. Not tomorrow — now. Not after the weekend — now. Every maternity unit has a triage line that operates 24 hours a day, 7 days a week. The midwives on triage are not annoyed by anxious callers. They would rather hear from you than not.
I called triage three times in my third trimester and apologised each time for 'wasting their time.' Every single midwife said the same thing: 'Please don't apologise, this is exactly what we're here for.' The third call caught reduced movement that led to an early induction. Call. Every time.
Pre-Eclampsia
Pre-eclampsia affects around 6% of pregnancies and usually develops in the second half. It is a condition involving high blood pressure and organ involvement — primarily the kidneys and liver — that can become life-threatening for both mother and baby if it goes undetected.
The difficulty with pre-eclampsia is that its early symptoms are easy to explain away. Many pregnant people experience headaches; many have swollen feet. It is the combination of symptoms, and particularly the neurological signs, that should trigger immediate action.
Warning signs to take seriously
- A severe headache that does not resolve with paracetamol
- Visual disturbances — flashing lights, blurred vision, or seeing spots
- Severe pain just below the ribs, particularly on the right side — indicating liver involvement
- Sudden severe swelling of the face, hands, or feet
- Nausea or vomiting alongside any of the above
- Generally feeling very unwell when you previously felt well
Mild swelling of the feet and ankles is common and normal, especially in warm weather or after standing for long periods. It is sudden-onset, severe, asymmetrical, or facial swelling — particularly when it accompanies other symptoms — that warrants urgent assessment.
Risk factors and prevention
- First pregnancy, multiple pregnancy (twins or triplets), age 40 or over
- BMI over 35, pre-existing hypertension, diabetes, or kidney disease
- Previous pre-eclampsia, or more than 10 years since your last pregnancy
Pre-eclampsia crept up so gradually I kept explaining the symptoms away. Swelling is normal in pregnancy. Headaches are normal. It was the visual disturbances that finally made me go in. I had severe PE. If something feels different from your normal pregnancy experience — go in.
Reduced Fetal Movement
Reduced fetal movement after 24 weeks is one of the most significant warning signs in the second half of pregnancy. Its importance is not widely enough communicated — and the consequences of not acting on it can be severe.
There is no specific number of movements per day that counts as "normal." What matters is your baby's individual pattern — the times they tend to be active, the nature of their movements, and roughly how often they move. By week 28, you should have a settled sense of this. A sustained change from your baby's personal pattern is a warning sign, regardless of what the movement count is in absolute terms.
Placenta Praevia and Placental Abruption
These are two distinct placental complications — both serious, both requiring medical management, and both worth understanding clearly.
Placenta praevia
Placenta praevia means the placenta is covering part or all of the cervix. It affects around 0.5% of pregnancies at term and is often identified at the 20-week anomaly scan. Most low-lying placentas detected at 20 weeks migrate upward as the uterus grows — a follow-up scan at 32–34 weeks will confirm the position. Where the placenta remains over the cervix at term, a planned caesarean section is required, as vaginal birth would cause life-threatening bleeding. The main symptom is painless bright red vaginal bleeding, often sudden. Call 999 if this happens — do not drive yourself.
Placental abruption
Placental abruption is when the placenta partially or completely detaches from the uterine wall before delivery. Symptoms include sudden severe abdominal pain (often constant rather than wave-like), a hard or tender uterus, and vaginal bleeding — though bleeding can sometimes be concealed. Risk factors include previous abruption, abdominal trauma, smoking, and pre-eclampsia. This is a medical emergency — call 999.
Preterm Labour (Before 37 Weeks)
Preterm birth occurs in roughly 8% of UK pregnancies. Recognising the signs early and seeking assessment promptly allows for interventions that can significantly improve outcomes — including steroid injections to mature the baby's lungs, medication to slow labour while they take effect, and transfer to a unit with appropriate neonatal facilities.
Warning signs to act on before 37 weeks
- Regular contractions, even if mild or painless
- A persistent low backache that is new or different from your usual discomfort
- A feeling of pressure or heaviness in the pelvis
- Unusual vaginal discharge — particularly watery, bloody, or mucousy
- Waters breaking before 37 weeks
If you experience any of these before 37 weeks, go directly to your maternity triage unit — do not wait to see if they resolve on their own. Even if it turns out not to be preterm labour, assessment is always appropriate.
Ectopic Pregnancy
An ectopic pregnancy — where a fertilised egg implants outside the uterus, usually in the fallopian tube — cannot develop into a viable pregnancy. If undetected, a rupturing ectopic can cause internal bleeding that is rapidly life-threatening. It affects around 1 in 100 pregnancies and typically presents between weeks 4 and 10.
Warning signs
- Sharp, persistent one-sided lower abdominal pain
- Vaginal bleeding — often light and darker in colour than a period
- Shoulder tip pain — referred pain from internal bleeding irritating the diaphragm
- Feeling faint, dizzy, or collapsing
Normal pregnancy symptoms tend to develop gradually, affect the body symmetrically, and feel consistent from day to day. Warning signs tend to be sudden in onset, severe, one-sided, or accompanied by other concerning features like bleeding, visual disturbance, or shoulder tip pain. When in doubt, the right action is always to call — there is no cost to calling when something turns out to be normal, and a significant cost to not calling when it is not.
No. This is one of the most important things to understand about maternity triage. The midwives there are specifically trained to assess whether your concern needs further investigation. They expect calls from anxious pregnant people and welcome them. The culture in maternity triage is concern for people who did not call when they should have — not irritation at people who called with something normal. Please call, every time.
HELLP syndrome is a severe complication of pre-eclampsia — the letters stand for Haemolysis, Elevated Liver enzymes, and Low Platelet count. It is rare but life-threatening. Symptoms include severe upper right abdominal pain, nausea, vomiting, and generally feeling unwell. It can occur without the high blood pressure typical of pre-eclampsia, which makes it harder to self-identify. It is diagnosed by blood tests and requires hospitalisation and usually delivery of the baby regardless of gestational age.