What HG actually is

You do not need to become a clinician. You need enough to stop doubting what you are seeing, and enough to ask for the right things. This is that much, and no more.

How it differs from morning sickness

These are the HER Foundation's own comparisons. They are about what she can still do, not about how bad the nausea feels:

• Work. With HG she is often unable to work for weeks or months, and may lose the job or be forced to resign. With morning sickness, people usually keep working, perhaps part-time.
• Daily life. With HG she may be unable to do simple chores or care for herself, including showering or driving, when symptoms are severe.
• Energy. Severe fatigue for weeks or months, with bed rest often a necessity.
• Relationships. Stated plainly by HER: relationships are often greatly strained and may dissolve, isolation is common and can lead to depression, and neglect or abuse of the mother can occur.
• Money. Financial loss from medical costs and lost income is part of the disease's damage, not a side issue.

Why it happens, and why it is not her fault

For decades the blame landed on hCG, the pregnancy hormone everyone has heard of. A 2023 study in Nature moved it. The cause is a hormone called GDF15, which the placenta makes in very large amounts in early pregnancy.

The second half is the part worth carrying. People genetically predisposed to HG carry variants that leave them with low GDF15 when they are not pregnant. That low everyday baseline is exactly what makes them hypersensitive to the surge when the placenta starts producing it. The illness is a mismatch: her ordinary hormone level, meeting a normal pregnancy.

So this is biology. It is not weakness. It is not anxiety. It is not something she can push through by trying harder, and it is not caused by how she feels about the pregnancy. The front page of this site says she is not overreacting. This is the reason why.

What the illness actually does

Repeated vomiting over weeks does more than empty a stomach. HER Foundation lists what clinicians look for: dehydration and starvation signs, electrolyte disturbances, vitamin deficiencies including thiamine and vitamin K, raised liver enzymes, and reduced blood volume.

Two complications are worth knowing by name, because they change what you ask for:

Refeeding syndrome is the other. If she has not been able to eat for weeks while vomiting, HER Foundation notes she is at high risk when food starts again. That is why feeding her back up is a clinical decision, not a family one.

What treatment usually involves

Treatment belongs to her clinicians, and this page names no doses. But knowing the shape of it helps you ask:

• Fluids, with vitamins in them. HER Foundation's guidance is explicit that IV nutrients such as thiamine should be given with IV fluids rather than fluids alone.
• Thiamine before dextrose. ACOG's guidance is that thiamine is given before dextrose infusion, to prevent Wernicke's. If a sugar-containing drip is being set up, it is fair to ask about this.
• Early and aggressive beats waiting. ACOG recommends treating nausea and vomiting of pregnancy early to stop it progressing to HG, and HER Foundation notes that women treated aggressively early are less likely to have life-threatening complications or a long recovery.
• Repeated dehydration is not neutral. It worsens the nausea, makes it more resistant to treatment, and reduces how well the medicines work.

Words you may hear

If the vomiting will not stop, the conversation moves on to routes that go around her stomach. Here is what the words mean. Which one she gets is a clinical decision and it belongs to her team, so this page defines them and stops there.

• Feeding tube (NG or NJ). A thin tube through the nose into the stomach, or further down into the gut, so nutrition goes in below the part that is vomiting.
• PICC line, or midline. A long intravenous line, used when fluids or nutrition are needed over weeks rather than days.
• TPN, total parenteral nutrition. Nutrition given straight into a vein rather than through the gut.

One thing to know before that conversation. HER Foundation states that both PICC lines and midlines carry a risk of clotting, because pregnancy itself makes blood clot more easily. It also states that midlines carry less risk of complications from sepsis than PICC lines. Her team weighs that against everything else it knows about her.

Her teeth

Months of vomiting bathes her teeth in stomach acid, and acid softens enamel. That is dental erosion, and it is permanent.

Brushing straight after she is sick makes it worse, because the brush scrubs away enamel while it is still soft. It is the opposite of what anyone's instinct says.

What to do instead, from the American Dental Association and Pregnancy Sickness Support: rinse with water, or with about a teaspoon of baking soda in a cup of water, which neutralises the acid. Then wait about an hour before brushing.

This is one you can simply set up for her. A glass of water and the baking soda solution, standing wherever she is being sick, refilled without being asked.

If she talks about ending the pregnancy

Pregnancy Sickness Support states that around 50% of those suffering HG consider termination at some point, and that around 10% of HG pregnancies end in termination.

PSS lists the reasons people reach that point: too unwell to continue, unable to get the care they need, physical health at risk, mental health deteriorating, or unable to face another HG pregnancy. Their own words are that "Termination feels like the last resort."

The most useful thing you can understand is this. If she says it out loud, it is not manipulation and it is not a threat. It is a measure of how ill she is. Treat it the way you would treat any other clinical emergency signal: it means getting her better treatment, and getting both of you support. It is not an argument to win.

If a pregnancy does end, PSS treats that as a loss which needs grieving, and offers counselling specifically for HG loss. Their words: "Counselling is for you whether your baby died 1 week or 10 years ago, you don't have to struggle alone."

Will it happen again?

Two respectable sets of numbers disagree here. This page is not going to pick one for you.

A Danish population study of 1,447,968 pregnancies between 1998 and 2018 found that 1.9% carried an HG diagnosis, and put recurrence at 26.0%. The charities put it far higher. HER Foundation says recurrence is as high as 80%, and that their own studies consistently find the recurrence risk exceeds 75%. Pregnancy Sickness Support says severe pregnancy sickness recurs in up to 80% of the same women.

They are counting different populations, not contradicting each other. The registry counts only what a hospital wrote down as an HG diagnosis, so it misses everyone treated at home or coded as ordinary nausea of pregnancy. The charities mostly hear from the worst and longest cases. Neither number is her odds.

What a family can control is the timing of treatment. PSS states there is good evidence that early, pre-emptive use of vitamin B6 plus a first-line medicine prevents the deterioration that leads to hospital admission. A 2013 randomised controlled trial found 2.5-fold fewer moderate-to-severe cases when treatment began before symptoms started, compared with beginning when symptoms first appeared.

So if there is ever a next time, the lever is a written plan agreed with her clinician before trying again, not after the vomiting starts. PSS publishes a preparation document for exactly that conversation. And HER Foundation names "you probably won't have it again" as a myth, which is worth saying plainly here too.

Verified August 2026 against the HER Foundation's clinical pages and ACOG's guidance on nausea and vomiting of pregnancy. Verified again 2026-09-04 for the GDF15 research, the recurrence figures, the dental guidance, the feeding and line vocabulary, and the termination figures. Sources are listed on the sources page. This is background for a caregiver, not medical advice. Her own clinicians know things this page cannot.