You have had lots of responses so this may not be necessary - if you can - read The Women's Room by Maryln French - though you might not 'see' all of it until later in life.
As a female, you are already disadvantaged in the workplace and in life due to structural stereotypes in our society. If you need evidence, take the picture you have in your head of the nanny and cleaner you might hire, look around at senior level in your husband's company and in yours and see what proportion are male / female and take at look at the school gates at drop off or pick up, next time you are passing - nursery might be different but I suspect not hugely so.
Having become pregnant, you have created a visual reminder to everyone around you that you are now a mother and that impacts your career and how people see you.
Taking maternity leave is another impact to your career that despite promises to the contrary, has an irreparable impact to your overall future earnings.
Your decision to have children was a joint decision, but are your family decisions truly joint, shared, and equal - shopping, cleaning, nursery, holidays, health care, welfare, christmas, birthdays, staying in touch with family etc . or is it... 'let's talk about X, where you talk, he approves, makes suggestions and you action, or you define the action, he carries it out but you check it. ..' You might be lucky .. you might truly have an equal relationship and this may be the first deviation from equality.
The response has been to suggest that you hire a nanny which actually just puts the ownership on another woman to take his share of the responsibility for the child but will likely leave you with the details to sort out, unless you too walk out at 8 and return at 6 and you take joint responsibility in the hours you are together at home.
I could go on and on and on.. and you may not see this yet in your relationship, but it will evolve, if you take on 100% of the drop offs and pick ups. You will be left with all illness cover, juggling holiday cover out of term time, scheduling the family holidays, covering INSET days, being primary contact, being the one who sorts all activities, playdates, homework support, school projects, concerts, sports day - though likely he will make a special effort on one or two days a year, be applauded for it at work, you will be grateful for his presence and his kids will be delighted to see him. If you think this will not happen to you - take a GOOD look around!!