MEXICO CITY, April 22 (Reuters) - Mexican breadmaker Bimbo's first-quarter net profit fell by about 42% from the year-ago period, the firm announced in a filing on Monday, citing foreign exchange effects and a weaker spending environment in North America for the smaller gain.

Net profit for the first three months of the year stood at 2.4 billion pesos ($143 million).

Revenues for the company, which sells buns, cakes, cookies, bagels and tortillas across more than 30 countries, shrunk 6% to reach 93.2 billion pesos.

Net sales excluding the impact of the foreign exchange rate were essentially flat, the company added in a separate statement, with its operations in Europe, Asia and Africa showing the biggest sales growth when currency swings are excluded.

Bimbo's North America margin contracted 160 basis points mainly due to the strong Mexican peso impacting costs of products imported from Mexico, weaker sales volumes and general inflation.

Adjusted core earnings, or earnings before interest, taxes, depreciation, and amortization (EBITDA), fell by nearly 8% to total 11.8 billion pesos.

($1 = 16.5310 Mexican pesos at end-March) (Reporting by Valentine Hilaire, Aida Pelaez Fernandez and Marion Giraldo; Writing by Kylie Madry; Editing by David Alire Garcia)