Best bet would be to talk to HR dept. at your work and find out from them. Remember that due to law against sex discrimination, which pregnancy discrimination counts as, they cannot sack you on the basis of you having another baby. If they do not offer you the same job you had prior to your leave, they have to offer a suitable alternative - ie similar benefits and skill set. I would think that maternity leave would be a break that does not interupt continuous employment because of all the discrimination legislation... but as I said, best to check this out with HR as, within what the law allows, all employers will vary.
Anyhoo, good luck with No. 2!