The sister was also given a jail term after it was established that the two siblings were committing incest.
According to court reports, Knowledge Mavhika, 19, proposed to make love to his 16-year-old sister and she accepted.
The two were involved in a relationship and slept together several times before the girl became pregnant.
Her grandmother Rumbidzai Ganyani, demanded to know who the father was. She was shocked to learn that her own grandson was responsible.
The grandmother took the matter to the police and the girl was taken to a hospital for a medical examination. The two were arrested.
Mavhika was sentenced to 12 months in prison six of which were suspended for five years on condition that he does not commit a similar offense.
The other six months were suspended on condition he performs 210 hours of community service.
The girl was sentenced to five months in prison, which was suspended for three years on condition that she does not commit a similar offense.