Why do I have bad breath in pregnancy?

Most of the causes the NHS lists start in your mouth, and pregnancy makes several of them more likely. The NHS lists the main causes of bad breath as strong-smelling or spicy food and drink; problems with your teeth or gums, such as gum disease, holes in your teeth or an infection; fasting or crash dieting; some medical conditions, like dry mouth, tonsillitis and acid reflux; and smoking.

Pregnancy pushes on that list from several directions at once. The American College of Obstetricians and Gynecologists (ACOG) says the physical changes of pregnancy can show up in the mouth as pregnancy gingivitis, tooth erosion, tooth decay and gum disease, and that approximately 40% of pregnant women have some form of periodontal (gum) disease. Add sickness, reflux and a dry mouth, and bad breath is an unsurprising result.

Common causes of bad breath in pregnancy and what the guidance suggests
Cause	What the sources say	What helps
Gum disease	ACOG lists pregnancy gingivitis and periodontitis among the oral changes of pregnancy	Brushing, cleaning between teeth daily, a dental check-up
Vomiting	Morning sickness is very common early on, and the NHS says it usually clears up by weeks 16 to 20	ACOG suggests rinsing with a baking soda solution to neutralise acid
Acid reflux	The NHS says indigestion is more common from 12 weeks and more likely later in pregnancy	Small meals more often, not eating within 3 hours of bed, propping your head and shoulders up
Dry mouth	The NHS names dehydration, and breathing through your mouth at night, for example with a blocked nose	Regular sips of cold water, sugar-free gum
Long gaps without eating	The NHS lists fasting or crash dieting as a cause	Regular meals and snacks

Gums

The NHS says gum disease can lead to bad breath and a bad taste in your mouth, as well as gums that bleed when you brush, floss or eat hard foods, and gums that become swollen, red and sore. A 2022 meta-analysis of 20 studies found that gums bled on probing in about two-thirds (67%) of pregnant women, and that this became gradually more common through pregnancy. The authors note that the studies varied widely. Our page on nosebleeds and bleeding gums in pregnancy covers the bleeding side.

Sickness, reflux and acid

Vomiting and reflux bring stomach acid into your mouth. For people with morning sickness, hyperemesis gravidarum or reflux late in pregnancy, ACOG suggests that antacids or rinsing with a baking soda solution may help neutralise the acid. See morning sickness: what actually helps and heartburn and indigestion in pregnancy.

Is bad breath an early sign of pregnancy?

It is not on the NHS's list of early signs. The NHS does list a metallic taste in your mouth and a sensitivity to certain smells, both of which usually start around 4 to 6 weeks. A heightened sense of smell may make you more aware of your own breath, but bad breath on its own does not suggest pregnancy. A test does. Our page on metallic taste and food aversions covers that early taste change.

Bad breath in the second and third trimester

If it gets worse as pregnancy goes on, two likely reasons both build later. The 2022 meta-analysis found bleeding gums became gradually more common through pregnancy, and the NHS says indigestion is more likely in the later stages and if you have been pregnant before. ACOG's advice on protecting your teeth mentions reflux in late pregnancy specifically.

What helps bad breath in pregnancy

The NHS's advice for bad breath is mostly about cleaning, and it all applies in pregnancy:

gently brush your teeth and gums at least twice a day for 2 minutes, with a fluoride toothpaste
gently clean your tongue once a day with a tongue scraper or cleaner
clean between your teeth with interdental brushes or floss at least once a day
spit after brushing rather than rinsing with water
use sugar-free mints or gum after strong-smelling food and drink
avoid lots of sugary food and drinks, and do not brush so hard your gums bleed

For a dry mouth, the NHS suggests taking regular sips of cold water, keeping water by your bed at night, sucking ice cubes and chewing sugar-free gum, and avoiding lots of caffeine and fizzy drinks.

Seeing a dentist while you're pregnant

Go. The NHS says to see a dentist and hygienist for regular check-ups, "especially if you're pregnant", and ACOG says dental care in pregnancy, including X-rays with shielding and local anaesthetic, is safe. ACOG also notes that treating gum disease in pregnancy has not been shown to reduce preterm birth, but is not linked to any harm and does improve the mother's oral health.

In England, the NHS says check-ups and treatment from a dentist are free while you are pregnant and for 1 year after you give birth. Ask your midwife or GP about the maternity exemption (MATEX) certificate, which gives you free NHS dental care and free prescriptions. Our free prescriptions and dental care calculator works out your dates. In the US, ACOG notes that Medicaid often covers dental visits during pregnancy, but coverage varies by state.

Our page on going to the dentist while pregnant covers X-rays and fillings in more detail.

When to see a dentist or GP about bad breath

The NHS says to see a dentist if you have:

bad breath that does not go away after treating it yourself for a few weeks
painful, bleeding or swollen gums
toothache or wobbly adult teeth

Ask for an urgent dental appointment, the NHS says, if gum disease comes with very sore and swollen gums, teeth becoming loose or falling out, ulcers or red patches in your mouth, or a lump in your mouth or on your lip.

See a GP if a dry mouth makes talking or eating difficult, has not improved after a few weeks of home treatment, or comes with needing to pee a lot. And call your midwife, GP or 111 if you are vomiting and cannot keep food or fluids down for 24 hours, or have very dark pee or have not had a pee in more than 8 hours.

Frequently asked questions

Is bad breath a sign of pregnancy?

Not one the NHS lists. Its early signs include a metallic taste in your mouth and a sensitivity to certain smells, which usually start around 4 to 6 weeks, but not bad breath. A heightened sense of smell may make you notice your breath more. Bad breath alone does not suggest pregnancy; a test is the way to find out.

Why is my breath worse in the third trimester?

Gums and reflux are two likely reasons. A 2022 meta-analysis found bleeding gums became more common as pregnancy went on, and the NHS says indigestion is more likely in the later stages. Brush twice a day, clean between your teeth, and see a dentist, which is free in England in pregnancy.

What is the best treatment for bad breath in pregnancy?

Cleaning, and a dentist. The NHS advises brushing twice a day with fluoride toothpaste, cleaning your tongue daily, cleaning between your teeth daily and regular check-ups. If you are being sick, ACOG suggests rinsing with a baking soda solution to neutralise acid. See a dentist if it has not gone after a few weeks.

Does bad breath in pregnancy mean a boy or a girl?

No. Bad breath comes from your mouth, gums and stomach, not from your baby, and a search of the medical literature found no study linking it to the baby's sex. It is one of many folk predictions we cover in our guide to old wives' tales about boy or girl.

Bad Breath in Pregnancy