My husband and I live way below our means. I come from a middle class family and have lived on a really meager salary for years when I lived abroad and when I went back to school.
When I married him, my mindset stayed the same.
That meant no expensive baby showers like in the States, or funny nursery porjects to dig into our budget. It was a straight forward plan with clear goals.
As soon as we got married, we followed the old and outdated (but useful to us) advice to live on the husband's earnings and use the wife's (mine) as "bonus" money (for capital investments or luxuries) because it would be expected to disappear once I got pregnant.
It worked for us because my husband did outearn me by about 2x, and by choice we have pretty traditional division of labor.
So we used my earnings to minimize our future expenses - we made a big downpayment on our property to minimize our monthly cost, we bought cars that would last and paid for them outright, etc.
We didn't save up a lot of extra cash for babies.
Though if you are in the good ol' USA be sure to budget appropriately for labor and delivery. It is IN-SANE what some families have to pay for a hospital birth.
After my first I ended up working about 1/3 time for a couple years, just to get out of the house. I expected to be a SAHM for the first 5 years or so - homemaking plus continuing to do the bookkeeping for my husband's business.
What happened is that it sort of became perminate.
From experience the first time around, the money I saved s by being at home is almost as much as I was making anyhow - more food grown/cooked at home, on-call for husband's business, cloth diapers (because I have time to do all that laundry), no daycare bill, plus ditching work expenses for me (gas, clothes, food).
I'm lucky in that we've always been able to more or less mindlessly save money for our entire marriage. A decent portion goes into retirement accounts, but our "emergency fund" at this point could last us a year at our current lifestyle.