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Extreme heat under climate change has already begun to threaten health, particularly for mothers and babies in the hottest parts of the world. When exposure occurs in utero, extreme heat can undermine child growth and development, leading to devastating later-life consequences for both health and socio-economic stability. Previous research, however, has often overlooked the role of humidity, which, when paired with extreme heat, can result in deadly heat stress and associated health complications. Understanding the relative effects of heat versus humid heat is important for understanding the magnitude and location of the effects of climate change, and for targeting interventions. I compare the impact of prenatal exposure to heat versus humid heat extremes on child height attainment in three South Asian countries (India, Bangladesh, and Nepal) using fine-scale climate records, trimester-level exposure identification, comprehensive data on 200,000 children from the Demographic and Health Surveys, and a rigorous fixed effects design. I find that extreme humid heat in the third trimester is five times more detrimental to height attainment than heat alone, and that maternal heat exposure in the period preceding pregnancy may have lasting negative impacts on growth trajectories after birth—a critical exposure period that has received little-to-no attention thus far with respect to child health. Specifically, the average child’s height-for-age Z-score declines by 0.002 units for every additional day in the third trimester that wet-bulb globe temperatures exceed 29°C. Combining these effects with new projections of wet-bulb globe temperature, I estimate that by 2050, climate change could increase the mean number of hot-humid days in the third trimester by 56.5% in my study region, pushing more than 930,000 additional children under 5 into stunting even before accounting for future population growth. This estimate shrinks to 315,000 children when I consider future exposure to heat alone, implying that failing to account for humidity may lead to significant underestimates of the true effects of extreme heat on child health. I further find that children without adequate sanitation access and whose mothers lack formal education or belong to systematically marginalized castes are more vulnerable to the adverse health effects of prenatal exposure to humid heat. My results provide new insight into which heat events are most dangerous for early life health and when, in a region where near-annual heat waves already affect millions and are projected to worsen under further climate change.

Apps for smartphones and tablet devices are increasingly important sites of innovation and the basis for monetization for digital platforms. Apple is the sole distributor of apps on iOS and prevents iOS users from downloading any apps from any source other than Apple’s own storefront, the App Store. Apple requires all in-app purchases to be made exclusively via Apple’s own proprietary in-app purchase (IAP) system and charges app developers a 30% commission. Apple also restricts developers from informing users of alternative (usually cheaper) purchasing possibilities outside of the app (“anti-steering provisions”). Epic, the creator of the popular online video game Fortnite, brought an antitrust case against Apple in the US district court (California) claiming that the exclusivity and anti-steering provisions amounted to maintenance of a monopoly, denial of an essential facility and unreasonable restraint of trade. This litigation raises broader antitrust questions regarding whether mobile ecosystems can be defined as separate markets and be subject to “monopolization” through the exercise of “intermediation power.” Like an aftermarket, this “lock in” on one side of the market can co-exist with a high degree of competition on the other side of the market.\ud \ud

Digital platforms often perform intermediation roles and control an ‘ecosystem’ of interdependent products or services on multisided markets. Market power can arise through the control of narrow proprietary ‘walled gardens’ where there are direct and indirect network effects, high switching costs, little multi-homing, information asymmetries and a high degree of consumer loyalty or inertia. This can give rise to a form ‘economic dependency’ which allows exploitation over an ‘installed base’. These ecosystems may or may not be defined as separate markets under traditional competition law but can be subject to ‘intermediation power’. Like an aftermarket, this ‘lock in’ on one side of the market can co-exist with a high degree of competition on the other side of the market. The paper will explore some of these issues in the context of current competition law actions in the EU, US and elsewhere concerning the fees and restrictive conditions imposed for in-app purchasing on smart phones and tablet devices on the Apple app store.