What causes nausea in pregnancy and what helps

Nausea in pregnancy is driven mostly by the hormone surge of the first trimester, and heat, strong food smells and a crowded commute can make it worse. Eat small and often, drink steadily through the day, and call your polyclinic doctor if you cannot keep fluids down.

Why does early pregnancy make you feel so sick?

Blame the hormones, mostly. Human chorionic gonadotropin rises steeply in the weeks after implantation, oestrogen climbs with it, and progesterone slows the whole digestive tract down so food sits longer than it used to.

ACOG puts the usual start of nausea and vomiting before nine weeks of pregnancy, which is often before anyone else knows you are expecting. The NHS expects most women to feel better by around weeks 16 to 20. The exact mechanism is still argued over.

Slower digestion also explains the heartburn and the sour taste that often arrive with the queasiness. An empty stomach makes it worse, which is why the first hour after waking is usually the hardest. Reflux and nausea feed each other.

If this is all new to you, the other first-weeks changes are worth reading about in our guide to the early signs of pregnancy.

What sets it off in Singapore?

Your sense of smell sharpens in early pregnancy, and this is a country built around food. The fryer at the hawker centre, the fish counter at the wet market, someone eating a curry puff beside you on the MRT, the bin chute landing on your floor, durian season in full swing. Any of these can turn a steady morning.

Petrol fumes at the taxi stand and the heavy air inside a packed bus do the same job. Scent is personal, so your trigger list will not match your sister's.

A few things that genuinely help:

• Travel off-peak if your job allows it, and stand near the door rather than deep in the carriage.
• Keep a sliced lemon or a tube of something citrus in your bag and breathe through it when a smell hits.
• Eat a plain biscuit before you leave the flat, so you are never commuting on an empty stomach.
• Ask whoever cooks at home to use the extractor fan and keep the kitchen door shut.

Does the heat make it worse?

It does, indirectly. Daytime temperatures in Singapore pass 30 °C on most days, with high humidity, which the National Environment Agency's climate records bear out, and sweat evaporates poorly in air that damp. You lose fluid all day without noticing.

Add vomiting to that and dehydration arrives much faster than it would in a cooler country. Dark urine, a dull headache, dizziness when you stand up and a dry mouth are the early signs. Check the colour. Pale straw is what you want.

Sip rather than gulp, because a large glass of water on a queasy stomach tends to come straight back. Cold water, ice chips and frozen fruit often go down when nothing else will. If you are vomiting repeatedly, an oral rehydration sachet from any Guardian or Unity pharmacy is more useful than plain water.

What should you eat, and when?

Small and frequent beats two big meals. Keep something dry by the bed and eat it before you sit up. Protein and starch tend to sit better than fat.

A Cochrane review of treatments for nausea and vomiting in early pregnancy found the evidence thin across the board, with some signal that ginger helps milder symptoms. Nothing works for everyone. Our round-up of pregnancy nausea remedies goes through the rest, and the list of foods to avoid during pregnancy is worth a look while your appetite is rearranging itself.

Why does brushing your teeth make you gag?

This one catches almost everybody and almost nobody warns you about it. A heightened gag reflex plus a strong mint or foaming toothpaste is a reliable way to start the morning at the sink.

Brush later in the morning rather than first thing, use a smaller brush head, and keep the paste off the back of your tongue. A paste you actually like helps too. Our Non-Fluoride Toothpaste is formulated with pregnant and breastfeeding mothers in mind. It is made without SLS, cleans gently with a soft lather, and leaves your breath crisp with natural mint.

Skipping brushing is the one thing you should not do. Pregnancy gums bleed and inflame more easily, and stomach acid from vomiting softens enamel. Rinse your mouth with plain water after being sick and wait about half an hour before you brush, so you are not scrubbing softened enamel. There is more on this in our guide to toothpaste in pregnancy.

When should you see a polyclinic doctor?

Ordinary morning sickness does not need a doctor. Several things alongside it do, and some of them need the same day.

Book an appointment, or go to a GP after hours, if you have:

• Kept nothing down, food or fluid, for a day.
• Lost weight, or stopped passing much urine.
• Pain or burning when you urinate, or blood in your urine. A urinary tract infection often brings nausea with it and needs antibiotics.
• Fever, blood in your vomit, or severe abdominal pain.
• Nausea that starts for the first time after the first trimester, especially with a headache, swelling or pain under the ribs on your right side. Those together want checking for pre-eclampsia without delay.

Polyclinics handle most of this and a referral onward is straightforward. If you are already booked with KK Women's and Children's Hospital or the National University Hospital, their obstetric services take urgent calls around the clock.

What is hyperemesis gravidarum?

Severe, relentless vomiting that leaves you dehydrated and losing weight has a name and a treatment. The NHS describes hyperemesis gravidarum as the extreme end of pregnancy sickness, and it does not resolve with crackers and rest.

Treatment is usually anti-sickness medication, fluids, and sometimes a short admission for a drip. KKH and NUH both manage it. Some women wait too long before asking, either because they were told sickness is normal or because a relative insisted it passes. It does pass, eventually. Dehydration in the meantime is the part that causes harm.

If you have been vomiting since this morning and nothing at all has stayed down, ring the clinic where you are booked before the day ends. Say how many times you have been sick and when you last passed urine. That sentence gets you seen.