How I Met Your Mother: The Real Reason Why Lily Disappeared In Season 4 (2024)

Alyson Hannigan portrayed Lily Aldrin for all nine seasons of How I Met Your Mother, but the character briefly disappeared in season 4 of the sitcom. Lily served as a primary figure in the series, having met central character Ted Mosby (Josh Radnor) while in college. It was there that she also befriended her future husband, Marshall Eriksen (Jason Segel), with whom she started a family during the events of the show. However, the Lily How I Met Your Mother absence during season 4 was noted as feeling deliberate by many fans — and it was.

In season 4, the recently-married Lily and Marshall realized they have opposing views on starting and raising a family. Ironically, at that time, Hannigan was already expanding her own family. Lily disappeared in How I Met Your Mother season 4, starting in the season's 20th episode, "Mobius Designs." She didn't return until episode 23, "As Fast as She Can." While many fans wondered why Lily wasn't in several episodes of How I Met Your Mother season 4, there's a very simple explanation — maternity leave.

Lily Disappeared Because Of Alyson Hannigan's Pregnancy

The How I Met Your Mother Star Took A Maternity Leave Break

Following the birth of her daughter in 2009, Alyson Hannigan had to take maternity leave and step away from How I Met Your Mother for a while. This led to her character missing a few episodes before finally returning for season 4's last two episodes. Instead of simply removing Lily from HIMYM season 4 storyline, the show provided a clever explanation by expanding on a cold open joke.

The season 4 HIMYM episode "Mosbius Designs," Barney kickstarted a major Lily How I Met Your Mother moment when he told her a dirty joke despite Ted and Marshall's warning that the content was "guy funny." Future Ted claimed that it was the dirtiest joke he ever heard, so he never really told his kids and, consequently, the audience what it was.

Barney's joke was so offensive that, upon hearing it, Lily immediately walked away and avoided the group for the next month. This, of course, was an added line to cleverly explain the character's disappearance in the series. Before that, the sitcom came up with hilarious ways to cover up Hannigan's pregnancy throughout season 4.

When Lily returned a few episodes later, she claimed that she had time to think about the dirty joke and realized that it was actually funny. That was until Barney said something else offensive, forcing her to walk away again — although she didn't vanish for several episodes this time around.

Alyson Hannigan Stuck Around During Her Second Pregnancy

The Show Used The Opportunity To Introduce Marshall And Lily's First Child

Alyson Hannigan was pregnant twice while part of the How I Met Your Mother cast, although the show only had to remove Lily for several episodes during season 4. The actress did not take an extended leave when she was pregnant for the second time in 2012 during How I Met Your Mother season 7. Instead, Hannigan's second pregnancy was written into HIMYM to pave the way for the birth of Marvin Waitforit Eriksen, the first child of Lily and Marshall.

This approach was much more natural and wasn't as jarring for those viewers who noted Lily's absence in season 4. What's more, the introduction of Marvin Jr. into HIMYM allowed the show to progress significantly, with Lily and Marshall's struggles during parenthood making for some of the best episodes of the show's latter seasons.

Did How I Met Your Mother Struggle Without Lily?

Lily's Absence Was Noticed By Many Viewers

While How I Met Your Mother didn't struggle with Lily's absence in season 4, it was noted by many viewers. As a sitcom, HIMYM is underpinned by the five central characters, and removing any one of them from the equation leads to something of a disruption in the balance. However, the way the show-runners covered for Alyson Hannigan not being present did lead to an incredibly funny running gag with Barney's joke.

Plus, the episodes Lily wasn't present in season 4 were nowhere near as controversial as the period in season 2 when she left Marshall and travelled to San Francisco to study art. To this day there are many How I Met Your Mother fans who consider this a backward move for the character, and one that dampened the dynamic of the group since Lily and Marshall represented a well-functioning, non-toxic couple that the show needed to counterbalance characters like womanizer Barney Stinson or serial dater/hopeless romantic Ted.

Alyson Hannigan Wasn't The Only HIMYM Cast Member To Start A Family During Season 4

Cobie Smulders Was Also Pregnant During Her How I Met Your Mother Run

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While Lily wasn't in HIMYM much because of Hannigan's pregnancy, Hannigan wasn't the only one on How I Met Your Mother to get pregnant. In fact, Cobie Smulders (Robin) was also pregnant during the series, and at the same time as Hannigan to boot. It's not uncommon for pregnant actresses to portray unpregnant characters, especially on long-running sitcoms like How I Met Your Mother.

Filmmakers use common tactics to hide pregnancies, such as baggy clothes and extra large handbags to place in front of their bellies. The second time Hannigan was pregnant, creators didn't have to worry, as her character was having a baby in How I Met Your Mother anyway.

Alyson Hannigan Was One Of Many Sitcom Stars To Hide A Baby Bump

While Alyson Hannigan's pregnancy was hidden due to Lily not being in HIMYM season 4 much, it's far from the only sitcom that has hidden an actor's pregnancy on screen. This happened in Seinfeld not once but twice, as the irreplaceable Julia Louis-Dreyfus, who plays Elaine was pregnant in season 3 and season 8 (via The Things). However, unlike Hannigan, Louis-Dreyfus is very much present in most of those seasons. The production worked around Louis-Dreyfus's pregnancy by dressing the actor in oversized clothing and wearing large bags, but it still felt natural, as the clothes looked like things that Elaine would wear.

Julie Bowen, who played Claire Dunphy in Modern Family, was pregnant with twins in the first episode. Whenever she's on screen, she's sitting behind cereal boxes or carrying loads of laundry. When Claire gives the direct-to-camera interviews on the sofa, which the show is known for, she holds a cushion. If it was any other show, studio executives likely wouldn't have hired her due to being pregnant. Bowen explained:

"I was pregnant with twins, and I kept thinking they weren’t going to hire me. They kept bringing me in over and over and sort of staring at my humungous belly, and I thought, 'I’m never getting this job'" (via People).

Courtney Cox, who famously plays Monica Gellar in Friends, was pregnant in the final season (via Insider). Ironically, this couldn't be written into the show because it was already established that Monica and Chandler couldn't conceive. However, the production worked around it similarly to how both Modern Family and Seinfeld hid their cast pregnancies. When Monica is standing up in Friends season 10, she is often holding her jacket in front of her stomach, or some other part of the set is obscuring the view. Hannigan hiding her pregnancy when playing Lily in How I Met Your Mother in season 4 is one of many instances in the industry.

How I Met Your Mother

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Drama

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How I Met Your Mother is a sitcom created initially for CBS by Carter Bays and Craig Thomas. Five friends living in New York City navigate their twenties and thirties as they try to find love, success, and purpose. The show is framed through one friend's eyes, Ted Mosby, as he retells the story of how he met his wife to his children.

Cast

Josh Radnor , Jason Segel , Cobie Smulders , Neil Patrick Harris , Alyson Hannigan , Bob Saget

Release Date

September 19, 2005

Seasons

9

Network

CBS

Writers

Carter Bays , Craig Thomas

Showrunner

Craig Thomas