This paper examines how co-workers’ fertility affects individual childbearing. Using matched employer-employee data from Italian social security records for 2016–2020, we estimate how fertility among colleagues in the same establishment and of similar age and occupation affects a worker’s probability of having a child. We exploit variation generated by the 2015 Jobs Act, which weakened employment protection for newly hired workers and reduced their fertility. Focusing on incumbent workers hired before the reform and using the share of colleagues hired after the reform as an instrument for peer fertility, we find that a one-percentage-point increase in peer fertility at time t-1 raises a worker’s probability of conceiving a child at time t by 0.2-0.4 percentage points, corresponding to a 6%–11% increase relative to the sample mean. A placebo test using colleagues in other establishments of the same firm yields no effect, consistent with direct workplace interaction playing a role. Estimated responses are concentrated among younger workers and at first births and are stronger among workers with longer tenure and in less competitive firms. Our findings indicate that the workplace is a relevant social context for fertility decisions and suggest that labor-market institutions may generate spillovers to workers not directly covered by policy changes.