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Nonsteroidal Anti-inflammatory Drugs/Analgesics and Pregnancy

Analgesics (or painkillers) include drugs like aspirin, paracetamol, and codeine based painkillers. They are the most common over-the-counter drugs.

NSAIDS are anti-inflammatory agents that are not steroids. In addition to anti-inflammatory actions, they have analgesic, antipyretic, and platelet-inhibitory actions. They are used primarily in the treatment of chronic arthritic conditions and certain soft tissue disorders associated with pain and inflammation.

Acetaminophen is widely used during pregnancy for pain relief and as an antipyretic due to its efficacy and minimal side effects. It crosses the placenta and believed to be non-teratogenic in therapeutic doses. By monitoring 50,282 mother-child pairs, 226 of which had 1 st trimester exposure to acetaminophen, no evidence was found for increased risk of birth defects due to acetaminophen. It is important to remember that as acetaminophen crosses the placenta, the foetus is theoretically at risk from maternal overdose. The antidote, N-acetylcystein was demonstrated to cross the placenta.

Aspirin has been shown by many studies to be the drug most frequently used during pregnancy. Consumption of aspirin during pregnancy may produce adverse effects in the mother, such as anaemia , haemorrhage and prolonged gestation and labour. A number of retrospective controlled and surveillance studies which included a large number of patients did not find any association between aspirin use during 1 st trimester and teratogenic effects.

Low dose aspirin is used to treat a variety of conditions such as systemic lupus erythematosus with lupus anticoagulant/anti phospholipid antibody syndrome to reduce the incidence of pregnancy loss , pregnancy-induced hypertension , preeclampsia/eclampsia and others. No foetal or neonatal toxicity was observed after chronic use of low dose aspirin. The use of high dose aspirin in the second half of pregnancy is more controversial. The main concerns being:

In summary, it may be desirable to discontinue aspirin one to two weeks prior to term to avoid aspirin-induced bleeding problems. If high dose aspirin is used during the second half of pregnancy, amniotic fluid volume and patency of foetal ductus arteriosus should be monitored by foetal cardiac ultrasound .

NSAIDS such as Indomethacin, Ibuprofen, Naproxen, Ketorolac are not considered teratogenic in animals or humans. Due to their effects on prostaglandins, they may cause premature closure of the ductus arteriosus , oligohydroamnion and bleeding complications. They are effective as tocolytic agents and have been used for the treatment of premature labour. They should be used with caution near term and careful follow-up for amniotic fluid volume and the patency of the ductus are mandatory.

Codeine is a widely used narcotic analgesic and antitussive. Many cold preparations and over-the counter medications contain codeine. It is not associated with a higher risk of congenital malformations in animals. In higher dose (100 mg/kg/day), foetal resorption, decreased foetal body weight and maternal toxicity were observed. Use of codeine near term may cause a narcotic withdrawal syndrome in the newborn, manifested as tremor, jitteriness, diarrhoea and poor feeding. During labour, neonatal respiratory depression can occur to the same magnitude as other narcotics.

Meperidine is not associated with increased incidence of birth defects . However, in light of its effect on foetal respiratory system, heart rate, and oxygen consumption, caution should be used when administered during labour Also, withdrawal symptoms and neonatal addiction are possible when used inappropriately during pregnancy.

à , an opioid analgesic, is not considered to be teratogenic in humans. Placental transfer of morphine is very rapid. As with other narcotics maternal addiction with subsequent signs of neonatal withdrawal are expected in chronic users. Respiratory depression, decreased oxygen consumption in the newborn were all observed in children born to mothers who received morphine during labour or used the drug chronically. Persistent behavioural abnormalities attributed to morphine alone have not been proven in humans.

The information in this page is presented in summarised form and has been taken from the following source(s):
1. Motherisk, The Hospital for Sick Children:

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NSAID & Pregnancy
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Contact Last modified: Jun 25 2002