I should preface this with a mention of Austen and fashion. The fashion speech she uses to delineate her characters is different from that which she uses in her letters, but in both she shows a knowledge of current styles, details, and garment names. So, I’m going to assume, nay state, that, while she is careful not to overly describe a particular style of dress that would instantly connect the reader to a specific year, she does use phrases and clothing item names that are extremely current for the time she is writing (with one delightful exception in Northanger Abbey that was probably deliberate).

So, when she mentions a tippet she would have been referring to the tippet of 1815. It’s possible that as she puts the word in Miss Bates mouth she means the article that Miss Bates would have known as a tippet. Fortunately for us, there is little to distinguish a 1790s tippet (of which Bonnie has provided excellent examples) and an 1810-1815 tippet with one slight caveat: in fashion, a word may mean one garment or accessory and then morph gently into another. And, two words may run in parallel to describe the same object. So, in 1809-1815 the word tippet is sometimes interchanged with the word pelerine. The pelerine is a small traingular shaped accessory that covers the shoulders. (It becomes quite popular after 1820 and gets quite large, along with everything else, in the 1830s. But in Austen’s time it was small.

It is not a garment or accessory that would be any use in concealing a pregnancy.

Another thing to consider is the time/place one would wear a tippet. Again, in 1810-1815 tippets are associated with carriage/walking dress, I.e. as an object worn over a coat, or on some occasions, in opera dress as a decorative covering for the neck and bosom. I have not seen, nor do I recall seeing, a tippet worn with dinner or ball dress which makes perfect sense: dancing with a tippet would be clumsy and difficult. (By the way, opera dress tends to be more lavish than evening/ball dress, no doubt because you either spend your time sitting or walking for a brief period (and showing off, of course) during the intervals.)

One other consideration: concealing a pregnancy in the years between 1810-1815 would be particularly challenging because of the way gowns were designed. The full gowns of the 1790s—those wonderful confections of volumninous yet gossamer-thin muslins with curls and feathers and turbans seeming to topple off heads—were cut neckline to hem and designed to be gathered in at the (high) waist with a drawstring with the inevitable results as Bonnie describes. But, the gowns of 1810-1815 were designed with quite a different silhouette and construction. They were composed of a separate bodice and skirt sewn together at the waist. The object was to achieve the look of a graceful columns supporting an ample bosom, that is, they were fitted through the bodice, with a skirt that was only slightly, or not at all, gathered in the front. In addition, the stays worn under these gowns were not meant to nip in the waist but rather to produce a smooth line. Neither were they heavily boned as in the previous century. In other words, the body shaping was minimal but extended in a smooth line from the under-bust to the hips—again, difficult to hide a pregnant belly.

As to matting, I cringe at the thought of that being used anywhere near bare skin. If she had said rags there might have been a case, but matting? Ouch. 

So, I make no comments about Jane’s state as determined by other clues, but in terms of fashion, I’d say no.

Oh, and the beautiful fur-edged red covering garment in the Nattier portrait would probably have been called a mantelet/mantlet.