Fertility Math: Replacement Rates and Projections

Global fertility rates aren’t just falling: the rate of decline is accelerating. From 2006 to 2016, fertility dropped gradually, but since 2016 the rate of decline has increased 4.5-fold. In many wealthy countries, fertility is now below 1.5. While we don’t notice it yet, in time that will mean the population halves every 60 years.

Rob Wiblin is already a parent and Luisa Rodriguez is about to be, which prompted the two hosts of the show to get together to chat about all things parenting — including why it is that far fewer people want to join them raising kids than did in the past.

Links to learn more, video, and full transcript: https://80k.info/lrrw

While “kids are too expensive” is the most common explanation, Rob argues that money can’t be the main driver of the change: richer people don’t have many more children now, and we see fertility rates crashing even in countries where people are getting much richer.

Instead, Rob points to a massive rise in the opportunity cost of time, increasing expectations parents have of themselves, and a global collapse in socialising and coupling up. In the EU, the rate of people aged 25–35 in relationships has dropped by 20% since 1990, which he thinks will “mechanically reduce the number of children.” The overall picture is a big shift in priorities: in the US in 1993, 61% of young people said parenting was an important part of a flourishing life for them, vs just 26% today.

That leads Rob and Luisa to discuss what they might do to make the burden of parenting more manageable and attractive to people, including themselves.

In this non-typical episode, we take a break from the usual heavy topics to discuss the personal side of bringing new humans into the world, including:

• Rob’s updated list of suggested purchases for new parents
• How parents could try to feel comfortable doing less
• How beliefs about childhood play have changed so radically
• What matters and doesn’t in childhood safety
• Why the decline in fertility might be impractical to reverse
• Whether we should care about a population crash in a world of AI automation

This episode was recorded on September 12, 2025.

Chapters:

• Cold open (00:00:00)
• We're hiring (00:01:26)
• Why did Luisa decide to have kids? (00:02:10)
• Ups and downs of pregnancy (00:04:15)
• Rob’s experience for the first couple years of parenthood (00:09:39)
• Fertility rates are massively declining (00:21:25)
• Why do fewer people want children? (00:29:20)
• Is parenting way harder now than it used to be? (00:38:56)
• Feeling guilty for not playing enough with our kids (00:48:07)
• Options for increasing fertility rates globally (01:00:03)
• Rob’s transition back to work after parental leave (01:12:07)
• AI and parenting (01:29:22)
• Screen time (01:42:49)
• Ways to screw up your kids (01:47:40)
• Highs and lows of parenting (01:49:55)
• Recommendations for babies or young kids (01:51:37)

Video and audio editing: Dominic Armstrong, Milo McGuire, Luke Monsour, and Simon Monsour
Music: CORBIT
Camera operator: Jeremy Chevillotte
Coordination, transcripts, and web: Katy Moore