Experts have found that at the start of the COVID-19 outbreak in early 2020, Americans chose not to become pregnant as they grappled with stay-at-home restrictions, anxiety, and economic hardship. Now, a new study led by researchers at NYU Grossman School of Medicine shows that some states actually experienced steeper decreases in fertility than others.

The findings revealed that nine months after the pandemic began, there were 18 fewer births a month per 100,000 women of reproductive age across the U.S. compared with the year before. However, after the second wave in 2021, fertility fell by roughly 9 monthly births per 100,000 women, which was similar to the rate at which national fertility had been decreasing prior to the pandemic.

“Our findings suggest that while the overall national fertility rate rebounded remarkably quickly after the initial COVID-19 wave, the initial declines by state were as polarized as the country as a whole,” said study co-lead author Sarah Adelman, MPH, a research associate in the Department of Pediatrics at NYU Langone Health.

According to the state-specific results, New York State experienced a massive fertility rate decline following the first wave, plunging from a pre-pandemic annual trend of 4 fewer monthly births per 100,000 women of reproductive age to roughly 76 fewer monthly births per 100,000 women. Delaware saw about 64 fewer monthly births for the same number of women and Maryland about 55 fewer monthly births per 100,000 women. Like they had been in New York, annual fertility rate decreases in these states were in the single digits prior to the coronavirus outbreak.

By contrast, following the first wave, Idaho, Montana, and Utah experienced a boost of up to 56 additional births each month per 100,000 women of reproductive age. This is despite the fact that fertility rates in these areas had also been trending downward in the years leading up to the pandemic.

Adelman says that while previous research has documented national fertility-rate declines following COVID-19, the new study, publishing online April 11 in the journal Human Reproduction, goes a step further, comparing changes among individual states and examining factors that may account for the different rates.

For the research, the study team analyzed data from the U.S. Centers for Disease Control and Prevention Bureau of Vital Statistics, the 2020 U.S. Census, and from the University of Virginia 2021 population estimates, to calculate fertility rate trends after each COVID-19 wave. The team then examined whether coronavirus case rates or other factors were the main drivers of fertility rate changes.

Contrary to their expectation, the severity of the coronavirus wave in each state appeared to have had little bearing on changes in that state’s fertility rate, the researchers say. Rather, demographic factors like racial composition and economic factors, including greater income inequality, higher percentage of college-degree earners, and large drops in employment at the start of the pandemic, negatively impacted rates.

The research team then examined states’ political leaning and a measure called the social distancing index (SDI), which tracked changes in people’s mobility following the first wave. They found that states with stronger social distancing responses and that were politically liberal had larger fertility rate declines following the first wave of the pandemic. When plotted on a graph, politically liberal places such as New York and the District of Columbia had the highest SDIs and lowest fertility rates, while more conservative states such as Idaho and Montana had the reverse.

“These results suggest that changes in a state’s fertility rates were not driven by COVID-19 cases themselves but rather by existing social, economic, and political disparities,” said co-lead author Mia Charifson, MA, a doctoral student in the Department of Population Health at NYU Langone.

“While these issues have always been linked with decisions about having children, they were clearly magnified by the pandemic, highlighting the need to address underlying social factors that constrain people’s ability to grow their families, especially during times of crisis,” added study senior author Linda Kahn, PhD, MPH.

Kahn, an assistant professor in the Departments of Pediatrics and Population Health at NYU Langone, cautions that since the researchers used state-level, population-wide data in their study, their findings cannot explain choices made by individuals.

Future research, she says, might examine more personal factors that influence decisions around pregnancy during times of crisis, such as student debt, job security, and access to childcare, in addition to existential concerns about climate change and political instability.