What causes bleeding between periods?
There are many reasons why you might be spotting, most of them of no cause for concern. However, spotting can indicate a more serious condition or injury, so if you’re concerned about something that’s new or unusual for you, or the flow is heavy, see your doctor.
Common causes include:
A common cause of abnormal uterine bleeding is a hormone imbalance. Teenagers and women in perimenopause (approaching menopause) are particularly likely to be affected by this, as are women in their 40s and 50s taking HRT (hormone replacement therapy).
Hormonal contraceptives and Polycystic Ovary Syndrome (PCOS) can also affect hormone levels (see below). It’s always a good idea to contact your doctor if you have a change in bleeding pattern so they can check for any underlying causes.
Spotting is common in the first 3 months of using contraception that contains hormones, with as many as 30%–50% of women reporting unscheduled bleeding.
Hormonal contraceptives include:
Progesterone only pills, or minipills, are more likely to cause breakthrough bleeding than combined pills, however, this generally settles down after a few months. It’s not a sign that your contraceptive isn’t working, and doctors advise continuing to take your medication as stopping it can lead to unplanned pregnancy.
You’re more likely to bleed if you miss a pill, your patch comes off, there’s a problem with your vaginal ring or implant, if you start new medication that interacts with your contraception, or if you are sick or have diarrhoea while taking the pill. Always consult your pharmacist or doctor before taking any new medication to check if it interacts with your pill.
Although a change in bleeding pattern is common in the first few months of taking hormonal contraception, it’s a good idea to make sure there aren’t any other underlying causes. Taking a pregnancy test to rule out pregnancy and making sure you have an up to date STI screen and smear test (if you are eligible) are all things you can check to rule out underlying causes. If your bleeding pattern doesn’t settle down or you have a change in your bleeding pattern after the first few months of taking your hormonal contraception, you should contact your doctor so they can check for any other possible causes.
Taking a “morning after” pill, such as Levonelle or ellaOne can cause disruption to your menstrual cycle as well as bleeding in-between periods. 10% of women report breakthrough bleeding after taking the pill, which is due to hormone imbalance and listed as a very common side effect. Implantation of a fertilised egg into the lining of the womb can also cause spotting, so you should always take a pregnancy test 3 weeks after any unprotected sex to rule out pregnancy.
Pregnancy and miscarriage
Light implantation bleeding is quite common in early pregnancy and happens when the embryo embeds itself in the lining of the womb. Changes in your cervix can also cause spotting. If you think you might be pregnant, take a test (available for free from sexual health services, some GPs or Brook centres, or to buy from pharmacists and some supermarkets).
Bleeding can be a sign of ectopic pregnancy (when the embryo starts to develop outside the womb), or miscarriage. If you have any vaginal blood loss while pregnant, you should contact your doctor, or midwife or call 111.
Spotting can be caused by sexually transmitted diseases including chlamydia, gonorrhoea, and HPV infection. If you think you might have an infection or have recently had unprotected sex with a new partner, you might consider getting tested. Speak to your doctor or visit a sexual health clinic or chemist to pick up a free STI self-testing kit.
Pelvic Inflammatory Disease (PID)
Breakthrough bleeding is a sign of PID, which develops if bacteria spreads from your vagina to your uterus, fallopian tubes or ovaries and causes an infection. This usually happens because of a sexually transmitted infection (STI) or if there’s been damage to your cervix following childbirth or a miscarriage. Other symptoms include stomach or pelvis pain, painful periods, a temperature and vaginal discharge. If you think you might have PID, see your doctor.
Around 3% of women experience spotting when they ovulate; which usually happens in the middle of their menstrual cycles. This is due to rapid fluctuations in hormones. Ovulation blood is likely to be light pink or light red in colour, due to mixing with the cervical fluid that women produce at this point in their cycle. It usually lasts between a few hours and a day. If you think you have ovulation bleeding, it’s still a good idea to contact your doctor to rule out any other causes.
If your vagina is dry, you might find you are sore and bleed after sex. Dryness can be caused by a number of factors; menopause, breastfeeding, some medication and chemotherapy, some medical conditions including diabetes, and having your womb removed. Your vagina may also become sore if you are not aroused before sex or if you use perfumed soaps or washes around your genital area. If you have any bleeding during or after sex contact your doctor.
Polycystic Ovary Syndrome (PCOS)
Polycystic Ovary Syndrome is a condition that affects the way women’s ovaries work. It’s usually caused by a hormone imbalance and can cause irregular or missed periods and lead to reduced fertility and cysts in the ovaries. Women with PCOS often have irregular or fewer periods and might experience spotting during the rest of their menstrual cycle. If you think you have symptoms of PCOS you should contact your doctor.
Fibroids are non-cancerous growths that grow in or around the uterus and can contribute to heavy menstrual flow and bleeding between periods. They’re very common – around 1 in 3 women will develop them at some point in their life – and vary in size. They often disappear without treatment, but if you think you may have them, you should see your GP.
Bleeding between periods can be a symptom of uterine (endometrial) or cervical polyps. Polyps are growths that occur in the inner lining of the uterus, or womb, or on the cervical canal. They’re usually benign (non-cancerous), but can become cancerous. If you suspect you might have polyps, you should see your doctor.
Endometrial, vaginal, vulval, ovarian, cervical and uterine cancers can cause bleeding, but these are rare. Older women are more at risk from these diseases. It’s always important to contact your doctor if you have a change in your vaginal bleeding pattern so they can check for these conditions.
Injuries to the vagina, cervix or uterus can lead to abnormal bleeding. Rough sex, inserting objects in the vagina, or a cervical screening (Pap smear) test might all cause tears or ruptures. If you are in pain, or the bleeding is heavy, seek urgent medical attention.
Other possible causes of vaginal bleeding include:
- Extreme stress
- recently having an abortion