If population continues to grow at it's present pace, there will be a point where this planet can no longer support the life on it. This would either mean that only those with access to food sources will survive leaving the less fortunate to starve to death or for everyone to starve to death at a slower pace.
Some countries already have an overpopulation problem and have already taken steps to slow or even reverse this. To me, it makes more sense to take action before it becomes a problem. It is better to have excess than to risk food shortages. If we wait till we get close to the limit, just one bad crop could cause shortages. Further, having excess means food becomes more affordable.
What I think we should do is implant something in newborns, as well as all other people, that prevents them from conceiving. When they mature, and can prove that they are capable to raise a child, they are put on a list of people who are eligible. From that list, only a limited number of people are selected from the top down. If selected, they can have a procedure done to remove the device and a child. Of course, after the child is born, the device is put back.
If we use such a method, there would be no such thing as an unplanned or unwanted pregnancy so there would no longer be an abortion issue. Another thing it would help prevent is children being born to parents who can not financially or otherwise provide the child with a proper upbringing. This would mean that every newborn has a good chance at a fulfilling life instead of so many having little if any hope. Of course one of the other benefits would be that with a sustainable population, nobody would ever fear starving as there would always be plenty for us.
Unfortunately many people suffer with infertility. That doesn't mean adoption is a good choice for them. Not everyone can love someone else's child. There is nothing wrong with recognizing that in yourself and choosing to bring your own child into the world. There are many others who will be amazing parents to adopted kids.
I don't think we should stop any kind of research which enable us to advance our knowledge of fertilization and biology. Of course more emphasis should be put on adoptions of children which are in danger to put them to a better home. But scientists can come up with all new ways to cure diseases after learning stuff from fertilization.
Many families want to have their own children and wouldn't have the means to choose adoption for financial reasons. They could have biases against different races or socio-economic backgrounds. There may be issues at orphanages or other child detention centers. Bonds form early and there may be distress outside of that.
It is my opinion that at no time should technology ever cease or be denied to a population. In terms of the exploding population, it is much cheaper and easier to look towards education of populations on birth control and safe sex practices. Money would also be better served to go back into these communities to build public health awareness and build an infrastructure for not just sexual health, but overall health. The ability to have one's own offspring should not be denied because there are those out there that are having children they cannot support. Education and better health care training should be funded to help slow the population boom.