About 295,000 ba­bies were born to un­au­thor­ized-im­mig­rant par­ents in 2013, mak­ing up 8 per­cent of the 3.9 million U.S. births that year, ac­cord­ing to a new, pre­lim­in­ary Pew Re­search Cen­ter es­tim­ate based on the latest avail­able fed­er­al gov­ern­ment data. This was a de­cline from a peak of 370,000 in 2007.

Births to un­au­thor­ized-im­mig­rant par­ents rose sharply from 1980 to the mid-2000s, but dipped since then, echo­ing over­all pop­u­la­tion trends for un­au­thor­ized im­mig­rants. In 2007, an es­tim­ated 9 per­cent of all U.S. ba­bies were born to un­au­thor­ized-im­mig­rant par­ents, mean­ing that at least one par­ent was an un­au­thor­ized im­mig­rant.

The 14th Amend­ment to the U.S. Con­sti­tu­tion, ad­op­ted in 1868, grants an auto­mat­ic right of cit­izen­ship to any­one born in the United States. But in re­cent years, some politi­cians have called for re­peal of birth­right cit­izen­ship, in­clud­ing Re­pub­lic­an pres­id­en­tial can­did­ate Don­ald Trump, who says that so-called an­chor ba­bies are a mag­net for il­leg­al im­mig­ra­tion.

A Pew Re­search sur­vey in Feb­ru­ary 2011 found that a ma­jor­ity of Amer­ic­ans (57 per­cent) op­posed chan­ging the Con­sti­tu­tion to end birth­right cit­izen­ship, while 39 per­cent favored such a change. That same sur­vey found that most Amer­ic­ans (87 per­cent) said they were aware of the con­sti­tu­tion­al guar­an­tee of birth­right cit­izen­ship.

There were an es­tim­ated 11.3 mil­lion un­au­thor­ized im­mig­rants liv­ing in the U.S. in March 2013, ac­cord­ing to a pre­lim­in­ary Pew Re­search es­tim­ate. They make up 4 per­cent of the pop­u­la­tion, but their share of births is high­er be­cause the im­mig­rants in­clude a high­er share of wo­men in their child­bear­ing years and have high­er birth rates than the U.S. pop­u­la­tion over­all.

These es­tim­ates are based on data from the U.S. Census Bur­eau’s Cur­rent Pop­u­la­tion Sur­vey and Amer­ic­an Com­munity Sur­vey, us­ing the widely ac­cep­ted “re­sid­ual meth­od­o­logy” em­ployed by Pew Re­search for many years.

Most chil­dren of un­au­thor­ized im­mig­rants in the U.S. are born here, and there­fore are cit­izens. In 2012, there were 4.5 mil­lion U.S.-born chil­dren young­er than 18 liv­ing with un­au­thor­ized-im­mig­rant par­ents. There also were 775,000 chil­dren young­er than 18 who were un­au­thor­ized im­mig­rants them­selves and lived with un­au­thor­ized-im­mig­rant par­ents. These totals do not count U.S.-born chil­dren of un­au­thor­ized im­mig­rants who do not live with their par­ents.

The na­tion’s un­au­thor­ized im­mig­rants are more likely than in the past to be long-term res­id­ents of the U.S., and are in­creas­ingly likely to live with U.S.-born chil­dren. In 2012, there were 4 mil­lion un­au­thor­ized-im­mig­rant adults who lived with their U.S.-born chil­dren, both minor and adult. They made up 38 per­cent of un­au­thor­ized im­mig­rant adults. By com­par­is­on, in 2000, 2.1 mil­lion un­au­thor­ized-im­mig­rant adults, or 30 per­cent of this group, lived with their U.S.-born chil­dren, minor and adult.

These new es­tim­ates, which in­clude a 2008 es­tim­ate of 355,000 births to un­au­thor­ized-im­mig­rant par­ents, dif­fer slightly from a pre­vi­ous es­tim­ate for 2008 of 340,000 births to un­au­thor­ized par­ents, be­cause they use dif­fer­ent data sources and meth­od­o­logy.