Many people who go through a pregnancy loss want to know why it happened. You might wonder if it was something you did or didn’t do. But in most cases, pregnancy loss before 20 weeks is not caused by anything you did.
Often, losses in early pregnancy happen because of chromosomal differences in the baby. These changes usually occur by chance and are outside anyone’s control.
In this section, we look at some of the known causes of pregnancy loss. Understanding them may help you make sense of what happened — but it’s also okay if no clear reason is found. Many people don’t get a definite answer, even after testing.
We also talk about what follow-up care might involve, and what to think about if planning a pregnancy in the future.
“What I needed most was for someone to simply say, ‘I’m sorry you’ve lost your baby.’
Just hearing those words would have helped me feel seen and acknowledged.”
Possible causes of pregnancy loss before 20 weeks
Here are some causes your care team might talk to you about:
It’s often not possible to know the exact reason a pregnancy ended. This can be hard to understand or accept, especially if you’re looking for answers. But it’s important to know that most losses are not caused by anything you did or didn’t do.
About two out of three pregnancy losses in the first trimester happen because of random changes in chromosomes. These changes affect how the baby develops and usually happen by chance — not because of anything the parents did.
- Chromosomal differences
Most early miscarriages happen when the baby has too many or too few chromosomes. These changes usually occur at fertilisation and stop the pregnancy from developing normally. - Hormonal imbalances
Hormones like progesterone help support a healthy pregnancy. If levels are too low, it may affect how the pregnancy grows. - Placental problems
If the placenta doesn’t form or attach properly, it may not give the baby the support it needs, which can lead to loss. - Infection
Some infections in the uterus or body can increase the risk of miscarriage, especially if they affect the baby’s development. - Cervical insufficiency
This is when the cervix opens too early in pregnancy, often without pain or warning. It can lead to second-trimester loss. Treatments may be available in future pregnancies.
Sometimes, even after testing, no clear reason is found.
Questions you might want to ask
You might want to ask your doctor, midwife, or specialist:
- What do we know so far about why the pregnancy ended?
- Are there any tests available or recommended for me or my partner?
- Could this affect future pregnancies?
- Is there anything I can do now or before trying again?
- When is it okay to start trying again?
- Where can I find support for how I’m feeling?
You don’t have to ask all these questions at once. Start with what feels right. You can always come back with more questions when you’re ready.
Learning about the possible causes of pregnancy loss can sometimes bring comfort or clarity. But it’s important to remember — in most cases, it’s not because of anything you did or didn’t do.
If you want to know more, your care provider can talk with you about possible tests. These may help find a reason for the loss, especially if you’ve had more than one. But sometimes, no clear answer is found — and that can be hard to accept.
Whatever your situation, it’s okay to take your time. You can ask questions, seek support, and make decisions in your own way. When you’re ready, there are steps you can take to care for your health and think about future pregnancy.
