Shane Watson's availability for the first Test against West Indies in Dominica remains unclear as he prepares for the birth of his second child in Sydney. Watson has delayed his departure for the Caribbean due to the impending arrival of the baby, and he will miss the only warm-up match ahead of the first Test, a three-day game starting in Antigua on Wednesday.

He hopes to have arrived in Dominica in time to be considered for selection for the first Test, but knows there is a possibility that by staying at home he will affect his chances.

"They've said that I don't have to play the tour game, but obviously there is going to have to be a certain amount of time for me to get there, if it works out that way, to be able to play the first Test," Watson said in Sydney on Friday. "Coming off playing Twenty20 cricket, and then it's a long flight and recovering from a long flight into a Test match, I'm going to have to have a decent enough sort of lead-up anyway to be right to go.

"There is no doubt there will be a certain cut-off date at some stage, but there will be physically alone to be able to be right for that Test match. But the most important thing for me right at this time is to be here for the birth of my second baby."

Fast bowler Ryan Harris will miss the whole West Indies series to be at home for the birth of his first child, but he is considered a certain selection for the Ashes campaign that follows. The situation is not quite as straightforward for Watson, who faces a challenge from fellow allrounder Mitchell Marsh and could open the door for his younger team-mate if he is unavailable.

Should Watson be available for the first Test, it is possible that he and Marsh would play alongside each other, with the potential for two spinners to be included on a likely slow surface - Fawad Ahmed and Nathan Lyon. Whatever the case, Watson knows that he has the full support of the coach Darren Lehmann to be at home for the birth.

"It's one of the things he said immediately when he came in," Watson said. "It's family first. Initially our partners were banned for the first couple of weeks [of the 2013 Ashes] when Mickey [Arthur] was in charge but he just said if your family is here you've got to make the most of spending time with them.

"Darren has always been very much family first and this is a perfect case for myself and Ryan. In the end it is just a game even though it's a game we all love so much. I know it's a really important time in my career as well, obviously the opportunities that are going to be there aren't always going to be there, there's no question. I do have to make the most of the opportunities I get leading into the Ashes as well but there is no question [the birth] is my priority."

Watson arrived in Sydney this week after his IPL campaign ended with the Rajasthan Royals. It was also announced that he had signed a three-year deal with the Sydney Thunder in the BBL, having previously been part of the Sydney Sixers and then Brisbane Heat squads.