Haven’t read replies so apologies for any repeat points. I’m a dog owner so not anti dog at all but!
Money. Mine costs me around £300 a month which includes a dog walker.
Extra cleaning and washing. All dogs smell
Dog crap on your lawn. Even with regular pick ups there are wet slimes ones that don’t pick up easily which is not ideal with babies and toddlers using the garden.
You will need to supervise dog/child interaction at all times which means having to isolate the dog when you can’t.
Toddlers and dogs are both unpredictable!
Training the dog is a huge time commitment but if you don’t train it well life is difficult.
Sone dogs like to chew especially puppies so you will need to keep toys and stuff out the way. Not easy with little ones to look after.
Regular exercise. You should probably set aside a couple of hours a day for walks. That means in the winter taking small children out in the rain and cold regardless everyday if your DH isn’t there to do it.
When you get back from a rain soaked walk you’ll need to rinse/dry off the dog whilst managing wet toddler clothes and pushchairs and yourself.
Restrictions on your activities. In the early puppy days you won’t be able to go out for very long and an adult dog shouldn’t be left for more than 4 hours a days.
Daycare/boarding costs for holidays, days out etc you are looking at £30 a day (ish) Dig boarders round my way book up fast I have to plan and book nearly a year in advance for my main holiday. It’s DS’s birthday soon and we want to go to London for the day. Despite messaging doggy day care two months ago they have no spaces which mean someone has to stay home and miss out.
Pet insurance, even with a full policy there a t&c’s which will likely find you quite out of pocket in the event of a claim.
Most importantly though your DH is being incredibly selfish. He wants a dog that he knows he won’t have to really take responsibility for and the real work will fall to you whilst you have a baby and toddler. That’s disgraceful.