Consumers suing Natera Inc. for deceptively advertising Spectrum preimplantation genetic tests saw their class allegations dismissed after a federal judge said they weren’t specific enough.

“The complaint alleges only the approximate dates of purchase and not when Plaintiffs viewed the alleged statements or where they viewed them,” Judge Jon S. Tigar of the US District Court for the Northern District of California said. He dismissed the complaint Monday, but gave the plaintiffs 21 days to amend their allegations.

Shannon Petersen and Erin Vedrode alleged Natera falsely advertised preimplantation genetic testing for the chromosomal disorder aneuploidy. The test is known as …