Background:  Most women use medications at some stage in their pregnancy. Medication nonadherence during pregnancy could be detrimental to both mother and fetus.
Aims:  To study the extent and nature of the use of prescribed medications during pregnancy and factors associated with medication nonadherence.
Methods:  All women ≥18 years presenting for their 36th week antenatal visit at the pregnancy clinic of a maternity hospital were invited to complete an anonymous questionnaire that contained 61 items, including the Morisky scale. Factors associated with nonadherence were identified in univariate analysis; factors with P < 0.1 were further analysed in a binary logistic regression model. Results:  The participants (n = 819) had a mean age of 30.8 ± 5.3 years. Most participants were born in Australia, lived with a partner, had university education, were nulliparous, carried one fetus and were nonsmokers. Of these participants, 322 (39.3%) reported a chronic health condition during pregnancy, the most common being asthma (104; 12.7%). Two hundred and seventeen (26.5%) were using prescribed medications, which included anti‐anaemics (68; 8.3%), medicines for chronic airway conditions (64; 7.8%), vitamins and minerals (59; 7.2%) and anti‐diabetics (43; 5.2%). Nonadherence was reported by 107 (59.1%) participants, mainly because of forgetting (79; 43.6%). Factors associated with nonadherence were having asthma (OR 0.26 (95% CI 0.095 – 0.72), P = 0.009) and using nonprescription dietary minerals (0.30 (0.10 – 0.87), P = 0.027). Conclusions:  Adherence to prescribed medicines during pregnancy is alarmingly low. Health professionals should be more proactive in promoting adherence and assisting women avoid potential fetal harm because of nonadherence.