Malachi does talk about a 'godly seed' so that's one purpose of marriage. But right out of the gate, my wife and I decided to try to hold off on having kids for a little while to spend some time together. We lived in Indonesia where it is the custom to try to get pregnant the first year of marriage, or else people think something is wrong with you.
I worked in an office and they have office boys over there. One of them wasn't a boy. He was middle aged. His job was to wash the dishes in the break room, make photocopies, etc. But he sat in the break room by the water cooler a lot of the time. When I'd go in there to get water, he'd say, "Sudah disi belum" which translate, "Has been filled with contents yet or not?" except it's not gibberish in Indonesian. He had to explain what he meant. he was asking if my wife was pregnant. He'd ask me that over and over. Other people in the organization would, too, not usually the ones I'd see everyday, just the ones I'd see by the elevator that I'd met or worked on some project with.
It's was slightly annoying at the water cooler, but I just realized they had babies the first year of marriage if they could. After a while people stopped asking. I'm not sure if the guy at the water cooler did. But one day a woman I hadn't seen in a while, from my wife's people-group, asked if there were any 'good news.' I said no to my wife being pregnant, but realized she was late, so maybe that was the case. I went home wonder if she were pregnant, and she was. We waited over a year and a half before we got pregnant. At that point, we were trying. We just keeping up the normal active pace of our activities without doing anything to prevent pregnancy.
But when I got married, I was so happy to get to be married to my wife, I wasn't really focused on having children that much. But at 23 or 24 a woman usually is still in that peak range of fertility. At that time, I probably would have been cool with just being married. I guess I wanted children, but it wasn't that urgent, but after over a year together, we decided to try.
For the other three kids, we weren't trying to have kids, but we weren't using the more effective methods of not having them because we either didn't like the method or had ethical qualms that hormonal birth control could cause abortions, not to mention weight gain and whatever health consequences that you can get from taking hormones taken from horse urine or wherever they get it.