Disclosure: I have 2 kids and am married.
As a whole, yes, the birth rate is declining. See this thread - more and more folks making the choice to not have any kids at all, and that brings the north rate down quick.
When we decided to have our second, we thought a long time about whether it made sense for the wife to keep working (she works 4 days a week). In the end, after child care expenses, we did come out slightly ahead with her working, so she kept at it. As they've gotten older, childcare costs have lessened (only parts of the day with school, higher class sizes allowed with older kids, etc...) I always chuckled when doing taxes, the program always asked are you sure, that seems large on the childcare amount.
To some of the points above, finding jobs that accomodate part time work or flexible hours is a challenge. I've chosen to work for an employer that rewards a work life balance, but that comes at a cost of lower pay compared to other employers. The flip side is I am paid fairly for the hours I work, and don't have the expectation of hours of work above and beyond... And healthcare costs are amazing. Looking at what I spend on healthcare compared to when I started working is frankly shocking.
I don't fault folks for choosing not to have kids - hey - your choice. I do get annoyed when others question why anyone should or would want to have kids. I've found it to be one of the most rewarding things - to be a father, and guide a young being into the right ways of the world.