Exhibit 99.3

1. Unaudited Pro Forma Condensed Combined Financial Information

The following unaudited pro forma condensed combined financial information presents the unaudited pro forma condensed combined balance sheet as of March 31, 2017 and the unaudited pro forma condensed combined statements of operations for the fiscal year ended December 31, 2016 and the three months ended March 31, 2017. The unaudited pro forma condensed combined financial information includes the historical results of Sientra, Inc. (“Sientra”, “Parent”, or the “Company”), a Delaware corporation, and Miramar Labs, Inc. (“Miramar”), a Delaware corporation, after giving pro forma effect to the Merger described in the following paragraphs and accompanying notes.

The unaudited pro forma condensed combined balance sheet as of March 31, 2017 and unaudited pro forma condensed combined statements of operations for the fiscal year ended December 31, 2016 and the three months ended March 31, 2017 are presented for informational purposes only and should be read in conjunction with the historical audited financial statements of Sientra and Miramar and related notes thereto. The adjustments reflected in our unaudited pro forma financial statements are based on available information and assumptions that we consider reasonable. Our unaudited pro forma financial statements do not purport to represent our financial position and results of operations that would actually have occurred if the Merger had been consummated on March 31, 2017 for the balance sheet, and January 1, 2016 for the statements of operations, nor do they project our financial position or results of operations for any future date or period.

The Merger

Pursuant to the terms of the Agreement and Plan of Merger, dated June 11, 2017, as amended by the Amendment No. 1 to Agreement and Plan of Merger dated June 25, 2017 (the “Merger Agreement”), among Sientra, Desert Acquisition Corporation, a Delaware corporation and wholly-owned subsidiary of Parent (“Purchaser”) and Miramar, Purchaser commenced a cash tender offer (the “Offer”) to acquire all of the outstanding shares of Miramar’s common stock (the “Shares”), par value $0.001 per share at a purchase price per Share of (i) $0.3149 per share, in cash, without interest (the “Cash Portion”) and (ii) the contractual contingent value right pursuant to the Contingent Value Rights Agreement in the form attached as Annex II to the Merger Agreement (“CVR Agreement”), to receive one or more contingent payments upon the achievement of certain milestones as set forth in the CVR Agreement, without interest (the “CVR Portion”), subject to any applicable withholding, upon the terms and subject to the conditions set forth in the Offer to Purchase, dated June 26, 2017, and in the related Letter of Transmittal.

The Offer expired at 8:00 a.m., Eastern Time, on Tuesday, July 25, 2017. According to Computershare Trust Company, N.A., the depositary for the Offer, as of the expiration time, an aggregate of 8,580,547 Shares were validly tendered and not properly withdrawn, representing approximately 91.9% of the total outstanding Shares on a diluted basis including Shares already owned by the Purchaser. As a result, the Minimum Condition (as defined in the Merger Agreement) was satisfied and all conditions to the Offer having been satisfied, Purchaser accepted all of the Shares that were validly tendered and not validly withdrawn for payment pursuant to the terms of the Offer.

Pursuant to the terms of the Merger Agreement, on July 25, 2017 (the “Acquisition Date”), Purchaser effected a “short form” merger under Section 253 of the Delaware General Corporation Law (“DGCL”), pursuant to which Purchaser merged with and into Miramar, with Miramar as the surviving corporation (the “Merger”).

As a result of the Merger, Shares that were not acquired in the Offer (other than Shares held by Miramar (or held in Miramar’s treasury), Company, Purchaser, any other wholly owned subsidiary of Parent, or any wholly owned subsidiary of Miramar, or Shares with respect to which appraisal rights are properly exercised under the DGCL) were converted into the right to receive the Cash Portion and the CVR Portion. As a result of the Merger, Miramar became a wholly owned subsidiary of Company.

Unaudited Pro Forma Condensed Combined Balance Sheet

As of March 31, 2017

(dollars in thousands)

Unaudited Pro Forma Condensed Consolidated Statement of Operations

For the fiscal year ended December 31, 2016

(dollars in thousands, except shares outstanding and per share amounts)

Unaudited Pro Forma Condensed Consolidated Statement of Operations

For the three months ended March 31, 2017

(dollars in thousands, except shares outstanding and per share amounts)

Notes to Unaudited Pro Forma Condensed Combined Financial Information

1. Basis of Presentation

The unaudited pro forma condensed combined financial information presents the pro forma effects of the Merger. The historical financial information of Sientra and Miramar are presented in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

The unaudited pro forma condensed combined balance sheet as of March 31, 2017 was prepared using the historical unaudited consolidated balance sheets of Sientra and Miramar as of March 31, 2017 and presents the combined financial position of Sientra and Miramar as if the Merger occurred on March 31, 2017. The unaudited pro forma condensed combined statements of operations for the fiscal year ended December 31, 2016 and the three months ended March 31, 2017 present the results of operations as if the Merger occurred on January 1, 2016.

Sientra’s historical financial information as of and for the three months ended March 31, 2017 and for the year ended December 31, 2016 are derived from Sientra’s unaudited Form 10-Q filed with the United States Securities and Exchange Commission (the “SEC”) on May 9, 2017 and audited Form 10-K filed with the SEC on March 14, 2017, respectively. Miramar’s historical financial information as of and for the three months ended March 31, 2017 and for the year ended December 31, 2016 are derived from Miramar’s unaudited Form 10-Q filed with the SEC on May 16, 2017 and audited Form 10-K filed with the SEC on March 17, 2017, respectively. This unaudited pro forma condensed combined financial information should be read in conjunction with the aforementioned financial statements.

The unaudited pro forma condensed combined financial information has been prepared using the acquisition method of accounting in accordance with the business combination accounting guidance as provided in Accounting Standards Codification (“ASC”) 805, Business Combinations, with Sientra treated as the accounting acquirer. The unaudited pro forma condensed combined financial information will differ from the final purchase accounting for a number of reasons, including the fact that the estimates of fair values of assets and liabilities acquired are preliminary and subject to change when the valuation and other studies are finalized. The differences that will occur between the preliminary estimates and the final purchase accounting could have a material impact on the accompanying unaudited pro forma condensed combined financial information.

The historical financial information has been adjusted to give effect to matters that are (i) directly attributable to the Merger, (ii) factually supportable and (iii) with respect to the statements of operations, expected to have a continuing impact on the operating results of the combined company. The pro forma adjustments are preliminary and based on estimates of the fair value and useful lives of the assets acquired and liabilities assumed and have been prepared to illustrate the estimated effect of the Merger. The final determination of the purchase price allocation will be based on the fair values of assets acquired and liabilities assumed as of July 25, 2017, and could result in a material change to the unaudited pro forma condensed combined financial information, including goodwill.

2. Significant Accounting Policies

The accounting policies used in the preparation of this unaudited pro forma condensed combined financial information are those set out in Sientra’s audited financial statements as of December 31, 2016. Management has determined that no significant adjustments are necessary to conform Miramar’s financial statements to the accounting policies used by Sientra in the preparation of the unaudited pro forma condensed combined financial information. Certain reclassifications have been reflected in the pro forma adjustments to conform Miramar’s presentation to Sientra’s in the unaudited pro forma condensed combined balance sheet. No conforming adjustments were determined for the unaudited pro forma condensed combined statements of operations. These reclassifications have no effect on previously reported total assets, total liabilities, and shareholders’ equity, or income from continuing operations of Sientra or Miramar.

This unaudited pro forma condensed combined financial information may not reflect all the adjustments necessary to conform the accounting policies of Miramar to those of Sientra as the Company is still in the process of conforming the accounting policies of Miramar to those of Sientra as of the date of this Current Report on 8-K/A.

3. Calculation of Purchase Consideration and Preliminary Purchase Price Allocation of the Merger

The fair value of consideration transferred on the Acquisition Date includes the value of the cash consideration, the deferred consideration and the contingent consideration as part of the Merger. The purchase consideration is as follows:

Preliminary Purchase Price Allocation

Under the acquisition method of accounting, the identifiable assets acquired and liabilities assumed of Miramar are recorded at the Acquisition Date fair values and added to those of Miramar. The pro forma adjustments are preliminary and based on estimates of the fair value and useful lives of the assets acquired and liabilities assumed and have been prepared to illustrate the estimated effect of the Merger. The allocation is dependent upon certain valuation and other studies that have not yet been finalized. Accordingly, the pro forma purchase price allocation is subject to further adjustment as additional information becomes available and as additional analyses and final valuations are completed.

The following table sets forth a preliminary allocation of the purchase consideration to the identifiable tangible and intangible assets acquired and liabilities assumed of Miramar based on Miramar’s July 25, 2017 balance sheet, with the excess recorded as goodwill:

Preliminary identifiable intangible assets in the pro forma financial information consist of the following:

The amortization related to these amortizable identifiable intangible assets is reflected as a pro forma adjustment in the unaudited pro forma condensed combined statements of operations based on the estimated useful lives above and as further described in Note 5(a). The identifiable intangible assets and related amortization are preliminary and are based on management’s estimates. As discussed above, the amount that will ultimately be allocated to identifiable intangible assets and liabilities, and the related amount of amortization, may differ materially from this preliminary allocation. In addition, the periods the amortization impacts will ultimately be based upon the periods in which the associated economic benefits or detriments are expected to be derived or, where appropriate, based on the use of a straight-line method. Therefore, the amount of amortization following the transaction may differ significantly between periods based upon the final value assigned and amortization methodology used for each identifiable intangible asset.

Any differences between the fair value of the consideration issued and the fair value of the assets acquired and liabilities assumed are recorded as goodwill. Goodwill is not amortized to earnings, but instead is reviewed for impairment annually, absent any indicators of impairment. Goodwill recognized in the Merger is not expected to be deductible for tax purposes.

The final determination of the purchase price allocation of the Merger will be based on Miramar’s net assets acquired as of the Acquisition Date. The purchase price allocation may change materially based on the receipt of more detailed information and as balances change between March 31, 2017 and July 25, 2017. Therefore, the actual allocations may differ from the pro forma adjustments presented.

4. Notes to Unaudited Pro Forma Condensed Combined Balance Sheet

5. Notes to Unaudited Pro Forma Condensed Combined Statements of Operations

A sensitivity analysis on interest expense for the year ended December 31, 2016 and for the three months ended March 31, 2017 has been performed to assess the effect of a change of 12.5 basis points of the hypothetical interest rate would have on the debt. Stated interest rates related to the new debt is LIBOR + 7.5%.

The following table shows the change in interest expense for the new debt: