Hydrops Fetalis

Overview

Hydrops fetalis (say: HY-drops fee-TAL-iss) is a condition where too much fluid builds up in a baby's body before birth or soon after birth. The extra fluid collects in spaces where it should not be — around the lungs, around the heart, inside the belly — and can also cause swelling of the skin. It is not an illness you can catch, and it is not caused by anything a parent did or did not do. Hydrops fetalis is a sign that something else is going on, so doctors work to find the underlying cause and support the baby at the same time.

No, it is rare. Estimates vary, but hydrops fetalis is thought to affect roughly 1 in every 1,000 to 4,000 pregnancies. Because it is uncommon, most pregnancies are not affected.

It affects babies before birth and newborns. It can happen in any pregnancy, but it is more likely in certain situations, such as when the pregnant person is Rh-negative and has not had preventative treatment, when there are twins, when there is a severe infection during pregnancy, or when the baby has a heart problem, a genetic condition, or severe anaemia (a low number of red blood cells).

Symptoms

Common symptoms

• Often there are no symptoms that the pregnant person can feel — the first clue is usually an ultrasound scan.
• A belly that grows faster than expected for the stage of pregnancy.
• Extra amniotic fluid (the fluid around the baby), which may make the bump feel very large or tight.
• Swelling in the pregnant person's hands, feet, or face, sometimes with headaches or blurred vision — this needs to be checked quickly.
• Feeling breathless or uncomfortable because of the extra fluid.
• Contractions or going into labour early.

Symptoms in children

• Swelling of the baby's skin, especially around the face, limbs, and belly.
• Pale or greyish skin colour.
• Fast or difficult breathing, grunting, or flaring of the nostrils.
• A swollen, firm belly, and an enlarged liver or spleen.
• Yellowing of the skin or eyes (jaundice).
• Limpness, poor feeding, or being very sleepy.
• A smaller-than-expected chest, which can make breathing harder.

Causes

Main causes

• Immune hydrops: the pregnant person's immune system makes antibodies that attack the baby's red blood cells, usually because of Rh or other blood group differences. This is now much less common thanks to preventative treatment.
• Heart problems in the baby, such as structural heart defects or an abnormal heart rhythm.
• Severe anaemia in the baby, sometimes caused by an infection such as parvovirus B19 (a common childhood virus, also called slapped cheek).
• Genetic or chromosomal conditions.
• Twin pregnancies where the babies share a placenta and one receives too much blood flow (twin-to-twin transfusion).
• Problems with the baby's lungs, kidneys, or other organs, or a structural abnormality.
• Rarely, tumours, metabolic (body chemistry) disorders, or liver disease in the baby.
• In some cases, no cause is ever found.

Risk factors

• Being Rh-negative without having had preventative treatment in a previous pregnancy or during this one.
• A previous pregnancy affected by hydrops fetalis or by severe anaemia in the baby.
• Expecting twins or more.
• Certain infections during pregnancy, including parvovirus B19.
• A family history of genetic conditions or heart defects.
• Some long-term health conditions in the pregnant person, such as diabetes or thyroid problems.
• Severe anaemia in the pregnant person.

When to see a doctor

See a doctor urgently if:

• You are told at a scan that there is extra fluid around the baby, an unusual heart trace, or a thickened placenta.
• You notice fewer baby movements than usual.
• You develop sudden swelling, a severe headache, or vision changes.
• You have contractions, fluid leaking, or any bleeding before your due date.
• Your newborn has trouble breathing, looks pale or blue, or is feeding poorly and very sleepy.

Book a routine appointment if:

• At your routine antenatal appointments, especially your first blood tests and ultrasound scans.
• If you have had a previous pregnancy affected by hydrops fetalis or a blood group problem — ask for an early specialist review.
• After your baby comes home, attend all follow-up appointments, even if your baby seems well.

Diagnosis

Hydrops fetalis is usually found during an ultrasound scan, often at a routine appointment. The scan shows extra fluid around the baby's organs or under the skin, and sometimes a thick placenta or a lot of amniotic fluid. If this is seen, you will be referred quickly to a fetal medicine team, who will look for the cause and talk with you about what it means for your baby and your pregnancy.

Tests that may be done

• Detailed ultrasound scans, sometimes repeated every few days or weeks.
• A specialised heart scan of the baby (fetal echocardiogram).
• Blood tests for the pregnant person, including blood group, antibody screening, and infection checks.
• Amniocentesis — a small sample of the fluid around the baby — to look for genetic or chromosomal conditions.
• Cordocentesis — a blood sample from the baby's umbilical cord — to check for anaemia and other problems.
• MRI scans of the baby in some cases.
• After birth, blood tests, X-rays, heart scans, and other tests on the newborn.

What to expect at your appointment

You may have several appointments in a short space of time, and some tests can take days or even a couple of weeks to come back. A team including fetal medicine specialists, midwives, newborn doctors, and sometimes a geneticist will explain each result and what choices are available. It is fine to ask questions, take notes, or bring someone with you. Ask for a clear summary of what is known so far and what happens next.

Treatment

Treatment depends on what is causing the fluid buildup, how far along the pregnancy is, and how the baby is doing. The aim is to treat the cause where possible, keep the baby safe, and plan the safest time and place for delivery. Care is usually given in a specialist centre with a newborn intensive care unit (NICU).

Self-care at home

• Keep all your appointments, including extra scans and blood tests.
• Rest when you can, and accept offers of practical help from family and friends.
• Note your baby's usual pattern of movements and report any change straight away.
• Write down your questions before appointments so you do not forget them.
• Ask your maternity team who to call, day or night, if something worries you.
• If you are expressing breast milk for a baby in NICU, ask the staff for help and support with this.

Medical treatments

Doctors may watch the baby closely with regular scans and heart monitoring. If the baby has anaemia, a blood transfusion can sometimes be given through the umbilical cord before birth. Extra fluid around the lungs or heart may be drained with a fine needle in some situations. If the cause is an abnormal heart rhythm, medicines can be given to the pregnant person to help steady the baby's heart. Infection-related causes may be treated, and when the baby is born, the newborn team may provide breathing support, fluids, and other care in intensive care. Your team will explain which of these options apply to you, along with the benefits and risks.

When is surgery considered?

Surgery is not usually the main treatment, but procedures may sometimes be offered — for example, draining fluid from around the baby's lungs or heart, or, in some twin pregnancies, treating the shared placenta. Occasionally, a newborn may need surgery after birth to correct a heart or lung problem that caused the fluid buildup. Your specialists will discuss whether any procedure is suitable for your baby.

Living with this condition

If your baby is in intensive care, days can feel long and unsettled. Try to set small routines: a set time for visiting or calling the unit, a notebook for updates, and short breaks to eat and rest. Ask the staff to explain each monitor, tube, and test — understanding what is happening often makes things feel more manageable. If your baby comes home, you may have frequent follow-up visits at first, so keep a simple folder with appointment dates and questions.

Lifestyle tips

• Accept practical help — meals, lifts, childcare for other children, or someone to sit with you.
• Keep a simple diary of updates and questions for the medical team.
• Stay in touch with work or school about what you need; you may be entitled to leave or support.
• Take breaks from searching online — reliable information and your care team are better guides than late-night searches.
• Keep up gentle movement and rest, and try to eat regularly even when you do not feel hungry.

Diet and exercise

No special diet or exercise prevents or cures hydrops fetalis. If you are pregnant, eat a balanced diet, drink enough water, and do gentle activity such as short walks, as advised by your midwife or doctor. If you are resting more than usual on medical advice, ask about ways to stay comfortable and reduce the risk of clots. If your baby is in intensive care or has come home, look after your own meals and sleep as much as you can — your health matters too.

Mental health and emotional wellbeing

It is very common to feel shock, fear, guilt, or grief when a baby has a serious condition, and partners and siblings often feel it too. You may feel numb, tearful, angry, or unable to sleep. These feelings are normal, and help is available. Talk to your midwife, doctor, or the hospital's psychology team, and ask about counselling. If you ever feel you cannot cope or have thoughts of harming yourself, contact your local emergency number or an urgent mental health service straight away — you deserve immediate support.

Prevention

Not every case can be prevented, and no parent is to blame. However, some causes can be reduced: Rh-related immune hydrops is largely prevented by an injection offered to Rh-negative pregnant people at set times in pregnancy and after birth or bleeding. Good hygiene (especially handwashing around young children) lowers the chance of catching parvovirus B19, and managing health conditions such as diabetes well in pregnancy helps too.

Vaccines

There is no vaccine for parvovirus B19, the infection most often linked to anaemia in the baby. Make sure your routine vaccinations are up to date before and during pregnancy — for example, rubella protection — and ask your midwife or pharmacist which vaccines are recommended and safe in pregnancy.

Screening programmes

Pregnant people are offered blood group and antibody screening early in pregnancy, along with routine ultrasound scans. These checks pick up many problems early. If you have had a previous baby with hydrops fetalis or a blood group problem, ask for an early referral to a fetal medicine team, as extra monitoring may be recommended.

Complications

If left untreated

• Severe fluid buildup can put strain on the baby's heart and make it hard for the lungs to work.
• There is a risk of the baby dying before birth (stillbirth) in the most serious cases.
• Early (premature) birth and the breathing and feeding problems that can come with it.
• Breathing difficulties and the need for breathing support after birth.
• Anaemia, jaundice, low blood sugar, or infection in the newborn.
• Some babies who survive have developmental or health issues that need long-term follow-up.

Long-term outlook

Hydrops fetalis is a serious condition, and it is honest to say that outcomes vary widely depending on the cause and how early it is found. The encouraging news is that many babies are now treated successfully, especially when the cause can be identified and managed, and when delivery happens in a specialist centre. Survival rates have improved a lot over recent decades. Babies who survive usually need follow-up checks as they grow, and some need extra support with development, hearing, or growth. Your medical team can give you the most accurate picture for your own situation.

Find support

External links open third-party websites. Ruqelo Health is not responsible for external content. Listing an organisation does not imply endorsement.