Frew (27) and her husband Trent are expecting their first child in August and with the season not starting until April, Frew has decided to hang up her bib for now.
Her departure will be a big blow to a side which is light on experience, and the cupboard appears bare as far as replacements go.
Frew, though sad to be moving off the court, is enthusiastic about the pregnancy.
"We are thrilled with the news and so excited to be embarking on this journey. It will be extremely hard for me to watch from the sidelines but, as much as netball and the Steel are a big part of my life, some things are even more important," she said.
"I am determined to help the team anyway I can during the season and it goes without saying I will be one of their biggest fans on the sideline."
Steel co-coach Natalie Avellino said Frew's departure does leave a big hole.
"Wendy has always been the ultimate team player and I know she has struggled with feelings of letting the team down. But this is such a special time for her and Trent and we are truly happy for them."
Avellino and co-coach Janine Southby have already started evaluating potential replacements, although there was not not much depth in the midcourt in New Zealand netball.
The Steel's midcourt now consists of Hayley Saunders, Courtney Tairi and Shannon Francois. Francois and Tairi were both invited to a Silver Ferns camp last week, and will be expected to make the step up to the starting seven.
Frew has been with the team since the ANZ Championship started in 2008.
