Hi M.,
I was in your husband's shoes, so I wanted to share my perspective.
I am a full-time working mother who is the primary breadwinner. I have 2 wonderful children (5 and 2yrs old); however, I do not want any more. There are a few considerations: cost to properly raise a child, quality time with the kids, quality time with your spouse, quality time for yourself, time to maintain/build your career, and time to manage their schedule in addition to yours.
I am very aware of the cost to raise a child -- and it's quite a bit when you're in a higher tax bracket and don't get any financial breaks. In addition to the obvious costs of food, housing, diapers, clothes, childcare, etc... there are "hidden" costs like additional health care expenses,cost for life insurance, etc. My DH is almost 41, I turn 40 this year. I wanted to retire yesterday; he would be happy to work until the day he dies. At this point, I need to work for AT LEAST another 25-35 years to support/help support them through their college education and fund my retirement. I'm tired already! ;-)
It's also very challenging to spend enough quality time with each child, devote enough time to grow at work, manage household and family obligations, take care of yourself, and care for your relationship with your spouse. The kids need your absolute attention as much as possible -- and there are only so many hours in the day.
Re: work, I find that I work off and on 24-hours/day, 7-days/week. It is very difficult to stay current with business requirements/trends/etc... and it makes it challenging to squeeze this into our daily lives. It's also very challenging to function on a couple of hours of interrupted sleep. even if I didn't have to get up each and every time, I would still be awake for part of the time each child wakes up. the ad-hoc sick days don't help here either. AND in today's competitve work environment, you're competing with everyone for a small bucket of money for raises/bonuses/etc. Not fun!
Time with my spouse is almost nonexistent. most conversations revolve around sports activies, birthday parties and play dates, family obligations, doctor appointments, health, etc.
Me time -- doesn't exist!
When my husband pressured me about it, I explained my concerns. I would be happy to have a 3rd child if I could spend more quality time with my children. This means that he would need to become the primary breadwinner so I could work part-time. In addition, he would need to figure out how to manage investments so that I could retire at a "decent" age and we could pay for or help the kids go to a good college in addition to whatever funds are needed to ensure they have a well-rounded life in general. AND he would need to become more active in managing and being responsible for the kids well being and activities (e.g, doctor appointment, school registrations, party invitations, purchasing of clothes, food preparation, laundry, homework, baby proofing, etc.). That was the end of that discussion.
hope this helps give you additional perspective on how your husband may be feeling... you may want to identify each of his concerns and propose ways to address them.
good luck!
--h