1) If you have two kids, you are less likely to get a job in the near term so the heavier financial burden is squarely on your hu*****and. Is he OK with that?
2) What's your hu*****and's income trajectory like? Is he expecting a decent income increase every year (say, 10%)? What matters is long term income and net wealth accumulation
3) Do you have a strong opinion about private school vs. public school? Good private schools cost around $30k a year per kid. 100K of income clearly won't do it (even for one kid). On the other hand, there are significant hidden costs, mostly in the form of real estate price and taxes, associated with good public schools (at least in my area). Here a single family house with 2,500sqf of living space can easily command a price tag of $1.2mm and above and real estate tax of $25-30k a year. Does it apply to where you live?
4) I once had a conversation with some co-workers and the consensus is that, on average, each kid will set you back $2 million of NPV when all said and done. The number is significantly less if you do not plan to send the kid to private schools AND you do not plan to expand your dwellings because of the kid.
In short, with 100k of gross income, your family can certainly get by. However, if you do not have meaningful amount of savings, you live in an expensive area, and your income level is not expected to appreciate significantly, I am afraid finances will put meaningful constraints on potential options on many things which could impact your quality of living and your children's future education. It is everybody's own decision whether this should discourage him/her from having another child. For example, in my family, I want number two regardless. My hu*****and, on the other hand, refuses to have number two unless our gross income exceeds $1mm a year.