Meghan Markle's thrifty $50 H&M maternity dress breaks internet

Meghan Markle's latest budget-friendly frock is further proof her maternity style knows no limits. Photo / Getty Images

Meghan Markle's flawless sense of style has long been a talking point, and her latest maternity look is no exception.

The Duchess of Sussex stepped out at Mayhew on Wednesday, an animal welfare charity in London of which she was made Patron of last week. The scheduled appearance — to meet with volunteers, beneficiaries and service animals — marked her first official visit in the new role.

The pregnant royal arrived in a monochromatic ensemble, pairing a cream Emporio Armani coat with a beige sweater dress, a Stella McCartney tote and suede slingback Manolo Blahniks.

The Duchess of Sussex paired an Armani coat with a fitted dress from H&M for an appearance in London. Photo / Getty Images

It didn't take long for adoring royal fans to ID Meghan's choice of frock as a budget-friendly H&M number from the fast fashion brand's new maternity collection, Mama.

The fine-knit dress retails for just $US34.99 ($51.70 NZD) and has now completely sold out online in the shade the Duchess sported.

Check out #MeghanMarkle rocking this H&M Maternity Dress! 😍 Shop her look and more here: https://t.co/olVKGkBxaj #HM pic.twitter.com/SOlNtYOaUF

— H&M USA (@hmusa) January 16, 2019

Meghan is wearing the @hm ‘Mama Fine Knit Dress’ ($34) https://t.co/8sucIaqVpb#DuchessofSussex #MeghanMarkle pic.twitter.com/HbRzPOVowP

— What Meghan Wore (@WhatMeghanWore) January 16, 2019

Meghan's impeccable taste in fashion often includes brands her loyal followers can shop for themselves, however this is the first time the Duchess of Sussex, 37, has worn a piece from H&M's in-house maternity line.

The former Suits star also enjoys pairing high-end pieces and custom creations from the likes of Givenchy, Alexander McQueen and Oscar de la Renta with affordable pieces by & Other Stories, Rothy's and ASOS.

On Monday, the 37-year-old stepped out during a visit to Birkenhead showcasing another affordable find from her enviable wardrobe. She paired a vivid red coat by Sentaler with a striking purple dress from popular Canadian brand Aritzia, which retails for just $204NZD and has already sold out.

Meghan Markle cradles her baby bump as she visits Birkenhead, England. Photo / Getty Images

It's a busy day for the Duke and Duchess of Sussex, who will attend a premiere of Cirque du Soleil's Totem tonight (local time) with Prince Harry in Support of Sentebale at the Royal Albert Hall.

The evening will raise awareness and funds for Sentebale's work with children and young people affected by HIV.

Earlier this week, Meghan revealed she was six months' pregnant and the royal baby was due at the end of April, or in early May.