I don't think this is correct; most of the US doesn't have any age limit on informal jobs like babysitting and yard work. It's typically legal for children of any age to work for their parents' business. My ten-year-old is sometimes keen to earn money by washing windows or raking leaves for our neighbors, and I don't see anything wrong with this as long as she can opt out when she wishes.

The ability to schedule when you want (as opposed to a therapist who only has a slot at 2:30 on Thursdays) is another benefit, especially compared to in-person therapy you need to travel to. I have a pet peeve about studies that don't count the cost to beneficiaries of taking time off work, or whatever else they'd be doing with their time, to travel to and from an appointment during the workday.

There are no whistleblower systems in place at any major EA orgs as far as I know

I’ve heard this claim repeatedly, but it’s not true that EA orgs have no whistleblower systems. 

I looked into this as part of this project on reforms at EA organizations: Resource on whistleblowing and other ways of escalating concerns

• Many organizations in EA have whistleblower policies, some of which are public in their bylaws (for example, GiveWell and ACE publish their whistleblower policies among other policies). EV US and EV UK have whistleblower policies that apply to all the projects under their umbrella (CEA, 80,000 Hours, etc.) This is just a normal thing for nonprofits; the IRS asks whether you have one even though they don't strictly require it, and you can look up on a nonprofit’s 990 whether they have such a policy. 
• Additionally, UK law, state law in many US states, and lots of other countries provide some legal protections for whistleblowers. Legal protection varies by state in the US, but is relatively strong in California.
• Neither government protections nor organizational policies cover all the scenarios where someone might reasonably want protection from negative effects of bringing a problem to light. But that seems to be the case in all industries, including in the nonprofit field in general, not something unusual about EA.
• I’m not aware of any EA organizations that provide financial rewards for whistleblowers, which seem like they’d be very tricky to administer without creating incentives you don't want. The main example of financial rewards that I’m aware of is that the US government provides large financial rewards to whistleblowers whose evidence leads to the conviction of some fraud cases.

I'm not sure if anybody ever figured out how much the authors of this paper were joking. https://www.dailymail.co.uk/sciencetech/article-2114430/Save-planet-genetically-engineering-humans-smaller-suggests-NYU-philosopher.html

Thank you for writing this up! 
It's helpful that you flag that the large majority of studies are done in the US. I would find it helpful in discussing interventions if the location is flagged more - for example, the cash transfers intervention is in rural Kenya. My impression is that these interventions don't generalize well across different settings.
 

Love this topic!

>Do these interventions lead to a permanent reduction in family size, or a temporary one?

Note that even if total number of children ends up the same, there are benefits to spacing children by at least 18 months in terms of health (mother has more chance to recover between pregnancies, mother and baby are better nourished, better care for older siblings). Families may also be able to better afford to educate children who are more widely spaced.

This isn't relevant to all the impacts, you list, though — still worth thinking about those separately!

Does "before/after" mean the kids came before the Nobel, or the Nobel came before the kids? (probably what you want is the work that earned the Nobel, which is harder to time.)

I'd also guess it's confounded by more intense careers and people who are more dedicated to spending a lot of time at work. I doubt you change outcomes much by taking a shorter leave, once your personality and career are already a given.

I did laugh at this — it's a helpful strategy for your career if you'd by default be doing more than half, and anti-helpful if not!

I could imagine benefits to overall productivity across the couple by allocating to whoever can most spare the time. When our childcare falls through, my husband and I work out who will handle what based on the timing of our meetings, who's done more lately, etc, rather than it defaulting to the mother.