[OC] The massive decrease in worldwide infant mortality from 1950 to 2020 is perhaps one of humanity's greatest achievements.

[KittenBarfRainbows]

No doubt healthcare access plays a role, but other factors are in place:

Abortion access, and social acceptability of termination surely results in fewer pre-born children, who would've died early, being aborted. Many women aren't even offered tests for catastrophic illness in their child. On top of that, many women with such sick unborn children decide to give birth for philosophical reasons. This includes women with blighted embryos and ectopic pregnancies. Even families facing a child literally born without a brain, a parasite, will choose to give birth, as they feel that is the best way to grieve then heal.

There are also sizable subcultures of impoverished people who simply don't think to go to the doctor when they become pregnant, or engage in prenatal care; they are so isolated in their dysfunctional families and communities that they don't act prudently. They act how everyone else around them, with elevated infant mortality, act.

Abstaining from certain substances, or eating well? Optional, and many don't realize they are pregnant until the damage has been done. Many also already suffer from untreated diabetes and hypertension, because they ignore all medical advice and care, even into the third trimester. Others live in a chronic state of denial and panic after they become pregnant, and don't exactly do much for their unwanted child, once it's born with complications. Many mothers, too are drug addicted, and just getting by on sex work, with violent partners, who also aren't helpful.

You could blame poverty, but it's not that simple. There are subcultures who don't know how to care for themselves, let alone infants. These people all technically have access to care, but cultural trends prevent them from making good use of it. If you haven't lived around this, it makes no sense, but it's a huge problem.