A large proportion of stillbirths seem to happen in otherwise healthy babies and the cause often can't be explained.
However, many stillbirths are linked to placental complications. This means that for some reason the placenta (the organ that links the baby's blood supply to the mother's and nourishes the baby in the womb) isn't functioning properly.
A poorly functioning placenta may be the direct cause of stillbirth, or it may contribute to it because the baby's growth has been held back.
If there have been problems with the placenta, stillborn babies are usually born perfectly formed, though often small. With more research, it's hoped that placental causes may become better understood, leading to better detection of placental problems and better care for these babies.
Other conditions that can cause stillbirth or may be associated with stillbirth include:
- bleeding (haemorrhage) before or during labour
- placental abruption – where the placenta separates from the womb before the baby is born (this may be associated with bleeding or abdominal pain)
- pre-eclampsia – a condition that causes high blood pressure in the mother
- a problem with the umbilical cord, which attaches the placenta to the baby's tummy button – the cord can slip down through the entrance of the womb before the baby is born (cord prolapse), or it can be wrapped around the baby and become knotted
- intrahepatic cholestasis of pregnancy (ICP) or obstetric cholestasis – a liver disorder during pregnancy characterised by severe itching
- a genetic physical defect in the baby
- pre-existing diabetes
- infection in the mother that also affects the baby
Around one in 10 stillbirths are caused by an infection. The most common type of infection is a bacterial infection that travels from the vagina into the womb (uterus). These bacteria include group B streptococcus, escherichia coli (E.coli), klebsiella, enterococcus, haemophilus influenza, chlamydia, and mycoplasma or ureaplasma.
Some bacterial infections, such as chlamydia and mycoplasma or ureaplasma, which are sexually transmitted infections (STIs), can be prevented using barrier contraception, such as condoms.
Other infections that can cause stillbirths include:
- rubella – commonly known as German measles
- flu – it's recommended that all pregnant women have the seasonal flu vaccine irrespective of their stage of pregnancy
- parvovirus B19 – this causes slapped cheek syndrome, a common childhood infection that's dangerous for pregnant women
- coxsackie virus – this can cause hand, foot and mouth disease in humans
- cytomegalovirus – a common virus spread through bodily fluids, such as saliva or urine, which often causes few symptoms in the mother
- herpes simplex – the virus that causes cold sores
- listeriosis – an infection that usually develops after eating food contaminated by bacteria called Listeria monocytogenes (listeria); see preventing stillbirth for more information about the foods to avoid during pregnancy
- leptospirosis – a bacterial infection spread by animals such as mice and rats
- Lyme disease – a bacterial infection spread by infected ticks
- Q fever – a bacterial infection caught from animals such as sheep, goats and cows
- toxoplasmosis – an infection caused by a parasite found in soil and cat faeces
- malaria – a serious tropical disease spread by mosquitoes
There are also a number of things that may increase your risk of having a stillborn baby, including:
Your midwife will check the growth and wellbeing of your baby at each antenatal appointment, and they'll plot your baby's growth on a chart to ensure he or she is continuing to grow.
Every baby is different and should grow to the size that's normal for him or her (some babies are naturally small). However, all babies should continue to grow steadily throughout the pregnancy.
If a baby is smaller than expected, or his or her growth pattern tails off as the pregnancy continues, it may be because the placenta isn't working properly. This increases the risk of stillbirth.
Problems with a baby's growth should be picked up during antenatal appointments. However, it's important to be aware of your baby's movements and let your midwife know immediately if you notice a reduction in the baby’s movements.
See preventing stillbirth for more information.