Connections of unbeaten superstar Black Caviar have asked not to know the sex of her first foal due in late September.

Black Caviar was retired last year after notching her 25th win in the Group One TJ Smith Stakes and was served by Darley stallion Exceed And Excel in the spring.

Part-owner Neil Werrett said Black Caviar's first pregnancy had progressed well at a stud at Scone in the Hunter Valley.

"She's going really well. All her scans have been positive and it's all looking good so far," Werrett said.

"We don't know what the sex is and we asked not to know either.

"She's a good doer and we've got her on a good diet and she only has to smell food and she puts weight on but she's looking good."

Werrett said Black Caviar's owners would spend the next few weeks planning her 2014 mating partner.

Black Caviar's connections have engaged breeding experts to assist them with their decision, which Werrett said would again be a choice of Australia's top stallions.

"Some of the studs come to us but we just go through a process of analysing the best crosses and choosing from there," Werrett said.

"It's the same ones as last year that will be in the mix.

"She could go to More Than Ready, go back to Exceed And Excel, go to Snitzel, High Chaparral is in the mix and there's one other."

Belle Couture will join her illustrious half-sister at stud this season following the retirement of the $2.6 million yearling after just four starts.

Belle Couture won a maiden at Caulfield on Easter Monday before injury hampered her in her final two runs at Flemington in May, prompting the early end to the three-year-old's career.