If you've never had issues with conception, than you have it easy. In this modern day, pregnancy complications and infertility are extremely common. It is often an emotionally, physically, and financially taxing situation to be in. Make sure not to make their burden any bigger than it already is by saying something that would upset them.
If someone is struggling with conception, it is likely that they have researched adoption already. Truly, stop and think about it. Could you really the first person who could have suggested this to them? Probably not. Better to just accept the path they are trying to pave without offering up your judgement on what would be best for them.
When things aren't going well, it is not always comforting to hear that the situation is out of your hands. Despite this person's possible believe in any religious or spiritual entities, suggesting that their case is up in the hands of a higher power is not necessarily calming to hear. In fact, it may just make them question the larger plan they think is at play for themselves. Stirring doubt and anxiety with pregnancy is not always a good mix.
Struggling with pregnancy is an extremely frustrating, captivating, and anxious experience. Trying to switch the person's focus might be a good idea at first, but you may quickly realize how it only upsets your friend. Oftentimes when trying to start a family, it is a very difficult commitment to make. They are finally ready to make the sacrifices related to starting a family. Saying that they can continue on with their regular lives/whatever usually takes up their time is extremely disheartening to hear. Best to just be supportive, positive, and a good listener.