Prescribed Medicines Commonly Used In Pregnancy

Main Category: Pregnancy / Obstetrics
Also Included In: Women's Health / Gynecology;  Pharmacy / Pharmacist
Article Date: 22 Feb 2008 - 1:00 PDT

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A large proportion of women use prescribed drugs shortly before or during pregnancy. Every fourth expectant father uses prescribed medicines shortly before conception. These findings come from a new study from the Norwegian Institute of Public Health (NIPH).

Many women do not realise they are pregnant before 2-3 weeks after conception so they may have used prescribed drugs unwittingly. There is still limited information about the safety or risk of use of drugs in pregnant women, or the possible effects of the father's medicinal use shortly before conception. It is therefore important to know which drugs are most widely used during pregnancy in Norway.

Prescribed medicines used by mothers and fathers before and during pregnancy are now mapped for over 100 000 pregnancies through a link from two of the NIPH's national health registers; the Norwegian Prescription Database (NorPD) and the Medical Birth Registry (MFR). Mothers were followed up for a 15 month period, from three months before conception to three months after birth; whilst each father's medicinal use was registered in the three months before conception.

6 out of 10 use prescribed drugs in pregnancy

Results from the study show that:

- 8 out of 10 women (83 %) had at least one drug dispensed in the course of the entire study period (including the three months before and after pregnancy).

- Nearly 6 out of 10 (57 %) were dispensed a drug during the actual pregnancy.

- 4 out of 10 women (39 %) were dispensed a drug in the three months before conception.

- During pregnancy, the number went down to 3 out of 10 during each trimester (33 % in the first trimester, 29 % in the second and third trimester).

- In the three first months after birth, the number of women who were prescribed drugs rose to nearly 6 out of 10 (57 %), mainly due to contraceptive requirements and antibiotics.

- 25 % of fathers were dispensed at least one drug in the three months before conception.

Reduction in psychopharmaceutical use in pregnancy

The study also shows which types of drugs are used in pregnancy.

- Most pregnant women used antibacterial drugs. Four out of 5 used penicillins, which are understood to be safe for use in pregnancy.

- Use of drugs such as painkillers, sedatives and anti-depressants (ATC-code N) fell by more than 60 % from three months before conception until the third trimester for women. This can be explained by a general reduction in the use of opioids, benzodiazepines and anti-depressives.

- Before pregnancy, 2.5 % of women used opioids (strong painkillers), but this was reduced to approximately 1 % during pregnancy.

- Before pregnancy, 1.8 % of women used anti-depressants, which dropped to 1.1 % in the first trimester and further to 0.5 % in the two last trimesters. 70 % of the anti-depressant users were prescribed SSRIs.

- 650 women used anti-epileptics as treatment for epilepsy during pregnancy. 40 % of these used lamotrigine, 23 % used carbamazepine and 17 % used valproate.

- The number of women who used drugs for serious lung conditions was quite stable during pregnancy, but in contrast to many other drug categories (for example antibiotics) the number of users fell after pregnancy. Asthma drug users were around 2 % during pregnancy, falling to 1.3 % after birth.

Linking the NorPD with MFR

The study is the first of many based on a link between two of the national health registers, NorPD and MFR, both maintained by the NIPH.

NorPD contains information on all prescribed drugs that have been dispensed to individual patients from a pharmacy since 2004.

Information on births was extracted from the MFR. This study includes all births registered in the MFR when pregnancy started from (and including) 30th March 2004 and ended before 1st January 2007.

"Prescription drug use among fathers and mothers before and during pregnancy. A population-based cohort study of 106,000 pregnancies in Norway 2004-06."
Engeland A, Bramness JG, Daltveit AK, Rønning M, Skurtveit S, Furu K.
British Journal of Clinical Pharmacology 2008.
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Norwegian Institute of Public Health