I only have one child but I have been there. I worked until I went into labor and had to return to work and school when he was only 2 months old. There is a lot of pressure out there and many employers will make you feel like you can't compete with other employees because of your children but you have to know your own value. As long as your performance outweighs your attendance you can be confident in that the company you work for is benefiting by having you as an employee and you don't have to worry about job security.
What kind of work do you do? Maybe you should consider finding another employer during your maternity leave. There are more understanding employers out there, you just have to find them. Be honest about your children when you interview and assure your employer that you more than make up for lost time with quality of work and productivity.
I have worked for employers on both sides of the fence and it makes all the difference. If your employer is closed minded and doesn't feel understanding about your children’s needs and continually pushes you to do more than what you can, it will...and I stress...IT WILL affect your home life and your children. Your stress level will be higher and you will continuously be worried about job security.
My suggestion...Prepare yourself to change jobs and try to find a small, possibly family-owned, company that values good work above attendance and you can move up quickly and still make good money without the stress or lack of security. That's what I did and by being a hard-working dedicated employee that always went the extra mile WHEN I COULD, I doubled my income in les than 2 years and now I have all the flexibility I need because my employer values me and my work ethic.