Satyanath, and Sergenti 2004; Stewart 2002). Sub-nationally, Dube and Vargas (2013) show how economic conditions in Colombian municipalities can trigger violence.

Comparing key municipal characteristics for places where there was ever an attack against those that never experienced one reveals a lack of significant differences in poverty (proxied by the share of unsatisfied basic needs), fiscal performance, and basic health services for children (proxied by the DPT vaccination rate), but municipalities that experience violence shocks are larger, are less rural and have fewer individuals receiving subsidized health insurance (which can suggest less eligible population or lower local resources for health). Because the endogeneity of municipal violence can be thought of as an omitted variable problem, I add these indicators as controls in the regression<sup>35</sup> Nonetheless, the variability of violence exposure through gestation within municipalities lessens the endogeneity problem as any potential municipal confounder would need to vary at the trimester level to bias the results. Following the strategy in Valente (2015), I also add a control for the cumulative attacks in each municipality three years (36 months) up to the beginning of the pregnancy ( p p p p p ); as this varies by municipality and date of conception, it should capture any time-trend in the occurrence of attacks; that is, any potential ii,mm,tt time-varying heterogeneity correlated with both changes in municipal violence over time, and pp birthweight. The main equation to estimate for the birthweight b p of child _i_ , conceived at time (month-year) _t_ , in municipality _m_ is as follows: ii,mm,tt bbhtt b p 1 2 3 1p p p p 2p p p p + 3p p p p 4p pcc p p p pp ymmy m (Eq.1) ii,mm,tt ii,mm,tt ii,mm,tt mm,tt mm,tt+3 mm,tt+6 bbhtt = αα+ ββ XX + ββ XX + ββ XX + δδ + δδ mm,tt+9 mm,tt−36 mmtth mm ii,mm,tt The terms δδ p p p + δδp ( _j=3,6,9_ pp) are the exposure to violence in each pregnancy trimester. I + γγ + γγ + γγ + εε estimate the terms separately, even though there is no full consensus on whether the impact of a mm,tt+jj stress shock is heterogeneous across the length of gestation (Persson and Rossin-Slater 2018) nor on the stage for which impacts should be visible.<sup>36</sup> The last trimester ends at birth, and because pregnancies are typically viable from the 24th week of gestation, or the end of the second trimester, the last one can be absent. The specification accounts for early births by interacting exposure to violence in the third trimester (p p p p ) with an indicator of the pregnancy not reaching such trimester ( ).<sup>37</sup> This allows to keep those pregnancies in the sample but without mm,tt+9 misrepresenting their exposure to violence, that is, without assuming that they had no exposure to ii,mm,tt an event in the last trimester, or that their exposure corresponded to the events that occurred in the mmppttp mm3 municipality in the months after their birth. The base coefficient ( 3) continues to be the parameter of interest for exposure to violence in this trimester.<sup>38</sup> δδ

> 35 The municipal controls vary by year or by survey round because of limited historical municipal data reported monthly, and sometimes even yearly. Yearly variables are linked with DHS on the year and month of birth: if the child was born after June, the value corresponds to that of the concurrent year; if the child was born before June, it corresponds to the previous year.

> 36 For instance, Mansour and Rees (2012) find effects for the third trimester, Valente (2015) for the second one, and Camacho (2008) and Quintana-Domeque and Ródenas-Serrano (2017) only for early-pregnancy.

> 37 In the sample, only 154 cases (0.52%).

> 38 Despite this, because gestational length is negatively associated with in utero shocks, there could be some bias introduced for correlated outcomes; for instance, mothers who are not exposed to stress can mechanically have higher birthweight because of the longer gestational length (Matsumoto 2018). In a robustness check, I try the alternative proposed by Matsumoto (2018) of using three full months for each pregnancy trimester, although the

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