here and here, medical sonography was invented in the late 1940s but was not used for pregnancies until the 1970s. Now, it's so common and easy that my wife and I already have 16 pictures of our baby on the fridge, and she's only just started her second trimester. We already have almost as many photos of my child before its birth than I have of the first few years of my life or my father has of practically his entire childhood.
This is just one of the many advances that adds up to the lowest infant mortality rate in history. Take a look at this chart from The Secret Peace:
In the couple years since I did the above research and published the book, more data resources are available online. Here's an article about a specific case study on Niger, which reduced its child mortality (which means children under 5 years, slightly different than infant mortality) nearly in half from 226 (22.6 percent) in 1998 to 128 (12.8 percent) in 2009. And the ever-excellent Gapminder shows this chart, which, if you hit "Play" on the bottom, lets you see the trend from 1950 to today for every single country at once! You can watch all the countries drop over time towards a better rate (and increase in wealth, which is also shown on the chart). In the earlier years, many of the countries have such a high rate that they are literally off the chart.
At first glance, our great success in decreasing infant mortality would seem to have a terrible side effect: too many people. We've all heard about the threat of overpopulation and what a drain we all are on the earth's resources. Luckily - surprisingly - fertility rates have been decreasing simultaneously.
cool page of infographics. The decrease in fertility rates is happening for many reasons, but one is a consequence of the decrease in infant mortality: the logic that if your child is more likely to survive and thrive, you don't need to have as many to get the same result (a child surviving to adulthood.)
So, all in all, it's a good time to be a baby. And personally, we can't wait to introduce our upcoming little one to a world that while very imperfect, continues inexorably to improve.