I have a baby! I didn't even notice his birth 3 months ago but I'm certain to have a fort in the future it seems. I was worried everyone was too old to give birth. His mother is 131 years old. Prime of life for a dwarf I suppose.
Still, without immigrants to fall back on I know I'm going to eventually wind up in a situation where I have 5 male dwarves and no hope.
The children will eventually grow up, marry and have kids of their own.
Maybe a nursery of some sort. Lock up 3 or 4 pairs of dwarves to keep producing the next generation.
Dwarfs only need to be married to reproduce (and they can marry as soon as they're adult, at twelve years). Being extremely busy may reduce the rates a bit, but on average, you can expect one baby every two years from every married couple. If there are few married dwarfs in your fort, that can become a problem, because at larger populations, dwarfs take a lot of encouraging to marry. My solution is to sequester prospective couples in a 2x2 room containing two beds (each assigned to one of them) and one or two nice pieces of furniture to admire. Lock them in until they're seriously hungry/thirsty, let them out to satisfy those needs, repeat; marriage takes somewhere between one and three seasons usually. Having compatible jobs helps a lot - marriage happens a lot faster between dwarfs of the same profession.
Always remember that dwarfs are totally monogamous - they only ever fall in love and marry once in their lives. Widows and widowers will never marry again, there's no point at all locking them up with prospective mates.