I read the actual research study that found a correlation between left-side sleeping and healthy babies, but they were really careful to explicitly discourage people from reading into it too far. It's correlative, not causal, and they described it more as "medically interesting" than anything else. I forget if it was the same study or a different one that showed that women who got up to pee were less likely to have miscarriages, but that one also came with a hefty warning that it was correlative, not causal.
I wouldn't be too worried about it, and in my unscientific opinion staying well rested is more important than sleeping in a particular position.
Whenever you read summaries of research, you have to be really careful about reading into things like "30% more/less likely to..." because without the original frequency you have no idea if that's even significant or not. If there's a 1 in 3 chance of something happening, a 30% shift is going to be huge. But if there's a 1 in 200,000 chance... 30% "more likely" is still pretty freaking unlikely.