Advising expectant mothers
Considering taking herbal medicines
Advise speaking to a healthcare professional (midwife, doctor or pharmacist) first. Avoiding diagnosis and conventional treatment could be harmful for mother or baby.
The safety of a herbal medicine may depend on its form and the way in which it is used. For instance, is it a tea or a concentrated extract? How will it be administered? Often, less is absorbed with topical use than with oral use.
Generally, advise avoiding herbal medicines during pregnancy unless they are considered to be essential.
See our useful advice on Assessing risk and informing the risk versus benefit decision for medicines in pregnancy.
Taking (or planning to take) herbal medicines
Advise choosing products from a reputable source and following the manufacturer’s instructions, especially the dosage advice.
It is important for women to inform the healthcare professionals involved in their antenatal care:
- which herbal medicines they are taking, and
- about any changes made to their medication
Many herbal medicines have not undergone rigorous testing. They may contain contaminants, including heavy metals, pesticides or conventional medicines. There may be little or nothing known about their effects during pregnancy. Advise women to tell a healthcare professional if they feel unwell when taking any herbal medicine.
Ensure women are aware that herbal medicines could interact with their conventional medication.
In the quantities usually found in foods, herbs that are commonly used in cooking are not expected to be harmful during pregnancy.
In large doses or concentrated forms, even commonly used herbs such as sage and garlic have the potential to cause harm. For example, some herbs affect oestrogen levels; others stimulate the muscle of the uterus.
Almond oil (Sweet almond)
Avoid use in medicinal amounts.
Some women apply almond oil to their abdomens to prevent or get rid of stretch marks. Regular use during pregnancy may be associated with giving birth early.
In a multicentre study, daily application of almond oil for at least three months during pregnancy was associated with giving birth early (before week 37).
Do not use to induce labour or for other reasons.
Traditionally, blue cohosh has been used to induce labour because it stimulates the uterus. When it is taken during pregnancy, blue cohosh may be toxic to the unborn baby and mother; malformations cannot be ruled out.
Adverse effects, including seizures, stroke, myocardial infarction, and hypoxic injury (due to lack of oxygen) have been seen in babies after their mothers used blue cohosh at, or in the weeks leading up to birth.
Stroke was reported in a newborn whose mother drank a tea made of blue cohosh. The tea contained a metabolite of cocaine, and cocaine use by pregnant women is one cause of perinatal stroke. It was unclear whether the cocaine metabolite came from the blue cohosh or was a contaminant in the tea.
Myocardial infarction (MI) associated with congestive heart failure and shock was reported in an infant whose mother had taken three times the recommended daily amount of blue cohosh tablets for three weeks to induce labour. Other causes of MI were ruled out.
Severe multi-organ hypoxic injury was reported in a neonate whose mother had taken an unknown dose of a blue and black cohosh herbal mixture. At the age of three months, the infant had lower limb spasticity and required nasogastric tube feeding.
It is best to avoid German chamomile (the type of chamomile used most often as a medicinal herb). There are no data on how much is safe to use. If it is used, a daily limit of 2 cups of herbal tea has been suggested.
German chamomile has been used during pregnancy for many years and is often taken as a tea or infusion for morning sickness. Use may result in an earlier onset of labour as it can increase the tone of uterine muscle.
In a study, women who were at least 40 weeks’ pregnant and took chamomile (type not specified) had a faster onset of labour than those in a control group.
German chamomile can cause allergic reactions.
Life threatening anaphylaxis (a severe allergic reaction) was reported in a woman who received an enema made from German chamomile. The baby had severe asphyxia and died the following day. Chamomile is usually taken orally, not by enema.
Roman chamomile may induce abortion. It could be unsafe to take medicinal amounts orally during pregnancy.
Roman chamomile can cause allergic reactions.
Avoid medicinal doses until further information is available.
Cranberry is taken orally to prevent urinary tract infections but there is not much reliable scientific information. In the amounts normally found in foods, cranberry would not be expected to cause problems.
There have been reports of vaginal bleeding in women who used cranberry in late pregnancy, but there is no known association.
In a questionnaire study, over 900 women said that they had used cranberry (dose and type unknown) during pregnancy. Using cranberry did not increase the risk of congenital malformations, stillbirth or neonatal death, pre-term delivery, low birth weight, babies being small for their gestational age, low Apgar score or neonatal infection.
A non-statistically significant association was made between using cranberry in the second or third trimester and vaginal bleeding (more than spotting) after pregnancy week 17.
To avoid risk, do not take echinacea during pregnancy.
Echinacea is used orally for colds and other upper respiratory infections. Reliable information on the safety of echinacea during pregnancy is limited. Short-term use (up to 7 days) may be safe.
There is no evidence that use during pregnancy (including early pregnancy) affects the risk of malformations, pre-term birth, low birth weight, babies being small for their gestational age, delivery method or foetal distress.
Two studies compared the outcomes of pregnant women who took echinacea during pregnancy with those of pregnant women who did not:
In the first study, no statistically significant differences were found between the groups for pregnancy outcome, delivery method, gestational age, birth weight or foetal distress.
In the second study, using echinacea did not increase the risk of pre-term birth, low birth weight, babies being small for their gestational age, or malformations.
Evening primrose oil
Avoid use – there is a lack of safety data.
Evening primrose oil has been used orally in pregnancy for pre-eclampsia and to speed cervical ripening. Women taking evening primrose oil orally late in pregnancy may be at greater risk of having interventions at delivery.
A study compared the pregnancy outcomes of 54 women who used evening primrose oil orally from week 37 of pregnancy and 54 women who did not. In the evening primrose oil group, there was a non-significantly greater risk of:
- prolonged rupture of membranes
- arrest of descent (no movement of the baby down the birth canal despite contractions and pushing)
- vacuum extraction
- being given oxytocin to stimulate the uterus
Evening primrose oil may inhibit platelet function (and therefore blood clotting) in new born infants. Ecchymoses (bruising) and petechiae (pin prick marks) were seen on the trunk, extremities and face of a new born baby whose mother had used evening primrose oil (and raspberry leaf tea) orally and vaginally in the week before delivery.
Avoid use in medicinal doses.
Fenugreek is used as a galactagogue (to stimulate milk production). It can stimulate contractions of the uterus and has hypoglycaemic effects.
There have been reports of malformations in the babies of women who ate fenugreek seeds during pregnancy.
Hydrocephalus, anencephaly, cleft palate and spina bifida have been reported in the babies of women who ate fenugreek seeds during pregnancy.
There are reports of babies being born with a distinctive maple syrup body odour when their mothers had eaten fenugreek before giving birth. This odour is a sign of maple syrup urine disorder (MSUD) so could lead to MSUD being suspected. However, the babies born to the mothers who had eaten fenugreek did not have any key clinical indicators of MSUD, and the odour disappeared within a few days of birth.
Flax (Flaxseed, Linseed)
There is not much information on the safety of medicinal doses of flaxseed. It is used for gastrointestinal disorders such as constipation and irritable bowel syndrome (IBS).
Flaxseed may have mild oestrogenic effects. It contains phytoestrogens, which resemble the oestrogens in the body and may affect the metabolism of oestrogen.
Pregnant women using flaxseed oil may be more likely to give birth prematurely. One study found that flax use during the last two trimesters of pregnancy was associated with an increased risk of pre-term birth.
It is probably safe to use ginger in doses of 1g a day or less at all stages of pregnancy.
NICE (National Institute for Health and Care Excellence) guidance suggests ginger as a non-drug option for mild-to-moderate nausea and vomiting in pregnancy.
Ginger is commonly used for pregnancy-related nausea, particularly during the first trimester. Overall, there is no evidence that ginger increases the risk of adverse outcomes, including congenital malformations, spontaneous abortion, stillbirth, low birth weight babies, earlier delivery.
According to the UK Teratology Information Service (UKTIS), three cohort studies, one case-control study and several small clinical trials found no increase in the incidence of adverse pregnancy outcomes, including congenital malformations when ginger was used during pregnancy.
In one of these studies, 187 women took ginger during the first trimester of pregnancy and 187 took non-teratogenic drugs. Live births, spontaneous abortions, still births, therapeutic abortions, birth weight, gestational age at birth were not significantly different between the groups.
Another of the studies was a survey in which 1020 women reported using ginger during pregnancy. The risk of congenital malformations, pre-term birth and low Apgar score was the same for women who had taken ginger and those who had not. A slightly greater percentage of women who had used ginger experienced vaginal bleeding (not severe) after week 17 of pregnancy.
Ginseng (Panax) is often used for its calming effects. Despite widespread use, there is little safety information. In traditional Chinese medicine, ginseng is contraindicated in pregnant and lactating women except for treating specific conditions.
There have been reports of hypertension and hypoglycaemia with ginseng in non-pregnant people.
The ginsenoside Rb1 found in ginseng has teratogenic effects (causes malformations) in animals.
Oestrogen-like effects of ginseng have been reported, for example vaginal bleeding in post-menopausal women.
Avoid drinking more than 2 or 3 cups of green tea each day.
Green tea contains caffeine. Blood levels of caffeine will be similar for the unborn baby and mother because it crosses the placenta.
High caffeine intakes may increase the risk of miscarriage and having low birth weight babies. Some studies have found an increased risk of miscarriage with caffeine intakes above 200mg/day.
A cup of green tea may contain 10 to 80mg caffeine.
Iron-rich herbs are used to satisfy the greater need for iron during pregnancy. If low iron levels are suspected, patients should contact their GPs to get their levels measured. An appropriate iron supplement can be prescribed if necessary.
Various iron-rich herb products are available. Their iron content may vary.
Iron-rich herb products may contain contaminants.
Avoid use in medicinal doses unless there is a good clinical reason for it.
Peppermint and peppermint oil have been used as medicines for over 300 years in the UK. Peppermint is often used for gastrointestinal disorders, including flatulence, heartburn, and stomach ache.
Some reviews suggest that large doses of peppermint may stimulate menstruation or abortion. Reports of these effects have not been found in the medical literature.
There is very little scientific information to support the safe use of peppermint and peppermint oil during pregnancy.
Avoid unless a healthcare professional is overseeing use.
Using raspberry leaf during pregnancy is common, but safety information supporting this use is limited. Raspberry leaf is often used to stimulate and ease labour, and to decrease the length of labour.
In one study, raspberry leaf was used safely from week 32 of pregnancy until after delivery. From week 32 of pregnancy until labour, 192 women were randomly assigned to take either raspberry leaf tablets (2.4g daily in 2 doses) or placebo. There were no differences between the groups for:
- birth weight of the baby
- Apgar score at five minutes
- presence of meconium in the amniotic fluid (indicates that the baby was under stress)
- mothers losing more than 600ml blood
- diastolic blood pressure of the mothers at 32 weeks
Raspberry leaf may either stimulate or relax smooth muscle such as the smooth muscle of the uterus. The action might depend on the muscle tissue involved and the dose used.
Raspberry leaf may have oestrogen-like action but this has not been shown in humans.
Avoid in amounts greater than those found in foods.
There is very little scientific information on the safety of rosehip (oral or topical) during pregnancy. Orally, it is taken to boost vitamin C levels in the body. Topically, it is used for stretch marks.
St. John’s wort (also called Hypericum perforatum)
Avoid until there is more scientific evidence of safety.
NICE (The National Institute for Health and Care Excellence) advises against prescribing or recommending that patients use St. John’s wort for depression, whether they are pregnant or not.
St. John’s wort is used for mild to moderate depression. It is not clear whether there is a link between St John’s wort use in pregnancy and malformations.
A German database of health insurance records provided information for a study in which details of about 1.4 million pregnancies were examined. There were 496 pregnancies in which developing babies had probably been exposed to St. John’s wort (reimbursement for St. John’s wort had been sought). Analysis of 312 of these suggested there may be a link between neural, cardiovascular and urinary malformations and St. John’s wort use during pregnancy, particularly in the first trimester.
Another study compared the outcomes of 54 St. John’s wort exposed pregnancies to:
- 54 pregnancies in which there was exposure to conventional antidepressants, and
- 54 pregnancies in which mothers were not known to have depression or take any teratogenic drugs
Rates of major malformation, foetal outcome, pre-term delivery and birth weight were not significantly different between the groups.
Using data from the Danish National Birth Cohort, a further study compared the outcomes of 38 St. John’s wort-exposed pregnancies with those of a group of 90,128 other women. Malformations, including hypospadias, bilateral hip dislocation and heart septum defects were seen in 8.1% in the St. John’s wort-exposed pregnancies and 3.3% of those in the comparator group. The difference was not significant (p=0.13).
St. John’s wort induces CYP 3A4 and P-glycoprotein. It interacts with many drugs, including oral contraceptives. Some of these interactions could be serious.
Avoid in medicinal doses.
Turmeric contains curcumin, which has anti-inflammatory effects. Curcumin is sometimes used for digestive disorders. In medicinal doses, turmeric may stimulate the uterus.
The quantities of turmeric commonly used in foods are not thought to be harmful.
Valerian is used for anxiety and insomnia. More scientific evidence of safety is needed.
Other herbal medicines
The European Medicines Agency’s website has information on the safety during pregnancy of over 160 herbal substances in its herbal monographs.
Reporting adverse effects
Everyone is encouraged to use the Yellow Card Site to report suspected adverse effects (including congenital abnormalities) following exposure during pregnancy to a herbal or complementary medicine.
Pregnancy outcome information
UK Teratology Information Service (UKTIS) provides detailed information on pregnancy outcomes for specific herbal remedies including ginger, peppermint oil and essential oils (outside the scope of this document). This information could help with discussions, risk assessments and decisions.
Each of the UKTIS summaries has corresponding Best Use of Medicine in Pregnancy (BUMPS) patient information.
The Royal College of Obstetricians and Gynaecologists (RCOG) has a patient information leaflet on pregnancy sickness.
The NHS website provides information on pregnancy-related conditions, including vomiting and morning sickness, indigestion and heartburn in pregnancy and stretch marks in pregnancy.
- Link to risk assessment article added