What a birth record contains
A birth record is a dated certification that a person was born. In the US, the record type you see depends on the era and jurisdiction. Church baptismal registers were often the only birth record kept before civil registration began, which in most states rolled out between roughly 1850 and 1915. Town and county clerks carried paper ledgers well into the 20th century; state-level registration followed later.
The fields you can usually expect: full name at birth, sex, date of birth, place of birth, parents' names (the mother's maiden name is the single most useful field for a genealogist), father's occupation, and the informant — often a midwife or the attending physician. Delayed birth certificates, common for anyone born before statewide registration began, are filed decades later and draw on witness affidavits, church records, and census pages as corroborating evidence.
Abbreviations and Latin on birth records
Early parish registers — especially Catholic and Lutheran — are dense with Latin. Common markers include nat. (natus, 'born'), bapt. (baptizatus, 'baptized'), and pat. (pater, 'father'). English-language ledgers lean on shorthand for occupations and relationships: Wm. for William, Jno. for John, and ux. (uxor) for 'wife of' when a mother is identified by her husband's name only.
Record-type markers at the top of a ledger column — b., bp., bn. — distinguish birth from baptism from burial on shared registers. Reading the column header carefully before interpreting dates saves hours of untangling later.
Where to look
Start with the county or town clerk for the jurisdiction where the birth occurred — many have digitized pre-1910 ledgers. State vital records offices hold the authoritative certificates from roughly 1910 onward, usually with a restricted-access window of 75 to 100 years. FamilySearch and the National Archives hold microfilmed copies of many county records at no cost; Ancestry and MyHeritage index many of the same sources.
For pre-civil-registration births, go to the church of the family's denomination. Diocesan and synodical archives hold ledgers that local parishes no longer possess.