Known as Louise or Marie Louise, her date of birth is not stated at her baptism, which took place at La Nativité de la Bienheureuse-Vierge-Marie parish church of La Prairie on the south shore of the St. Lawrence River across from Montreal. 
The fourth child and third daughter of Pierre Lefebvre by his wife Marie Louise Brosseau, Louise had three older siblings, Suzanne, Marguerite and Pierre, and three younger ones, Anne Catherine, Pierre and Jean Marie.
Here’s my transcription of her baptism record, above:
L’an 1716 Le 1er May ay baptisé une fille de pierre / Lefevre et marie Louise Brosseau ses pere et mere [mariy?] / [ombte?] à Laquelle on a donné le nom de Louise, Le parr- / ain a été Louis Bouchard, La maraine marg. Lefevre / veve de pierre bourdeau, a été present pierre brion qui / a declaré ne savoir signer de ce enquis. [signed Gaschier curé]
My English translation:
Year 1716 The 1st May was baptized a daughter of pierre / Lefevre and marie Louise Brosseau her father and mother [mariy?] / [ombte?] to whom we gave the name of Louise, The god- / father was Louis Bouchard, The godmother marg. Lefevre / widow of pierre bourdeau, was present pierre brion who / declared he could not sign [his name] as was inquired [signed Gaschier parish priest]
In 1737, Louise married Pierre Roy, by whom she had ten children. She died in 1754 in St-Constant.
1. "Québec, registres paroissiaux catholiques, 1621-1979," database with images, FamilySearch (https://familysearch.org/pal:/MM9.3.1/TH-1961-28005-33062-8?cc=1321742 : accessed 15 April 2016), La Prairie > Nativité-de-la-Prairie-de-la-Magdeleine > Baptêmes, mariages, sépultures 1670-1755 > image 130 of 608; nos paroisses de Église Catholique, Quebec (Catholic Church parishes, Quebec).
Copyright © 2016, Yvonne Demoskoff.