A Sydney court has heard champion water polo player Keli Lane murdered her daughter because she did not want to dent her career or sex life.

In his opening address to the Supreme Court jury, prosecutor Mark Tedeschi QC said Lane had an overriding ambition to represent Australia at the 2000 Olympics.

The 35-year-old is on trial for the murder of her two-day-old daughter Tegan, who was last seen when her mother was discharged from hospital in 1996.

The prosecutor said Lane kept five pregnancies a secret from her family and gave birth to one child a day after playing in a final.

The court heard that two of her pregnancies were terminated and that Tegan was murdered within three hours of her mother leaving hospital and then going to a wedding that night.

Lane cried at times in the dock. She is on bail and made no comment outside court when she left with her legal team.

She has pleaded not guilty to a charge of murder and to three counts of perjury.

Mr Tedeschi is continuing his opening before Justice Anthony Whealy.