The GP also did not check the woman's blood pressure at any time over the following seven months of prescribing repeat prescriptions, after the woman had fallen pregnant.
The medications rang alarm bells with a midwife in June 2014, prompting the patient to discuss them with a nurse because her doctor was unavailable.
The nurse passed on a message from the doctor suggesting she should come off fluoxetine but keep up with the other medications.
She was later advised to stop taking all three of the drugs at the maternity unit.
The GP told the commission she had let the patient and herself down.
"I referred her for antenatal blood tests and to a midwife. However, I had a lapse of concentration and didn't address her prescriptions ... I let the patient and myself down. I cannot explain why this happened."
Dr Hill said the conversation between the nurse and patient was also a concern, saying "a culture of nurses not questioning medical colleagues is a disservice to both professions and to the patients to whom they owe a duty of care".
The GP was found to be in breach of the Code of Health and Disability Services Comsumers' Rights.