Many pregnancies have been featured in Lost. Additionally, unknown conditions on the Island have led to fertility problems among the Others, as well as an immune system related condition that causes women who become pregnant on the Island to die. Notably, Kate lied and claimed she was pregnant with Aaron at the time of boarding Flight 815, to explain Claire's baby when she was rescued as part of the Oceanic Six; this credibility of her story is questioned in the Season 4 DVD extra The Oceanic Six: A Conspiracy of Lies.
In the outside world, Juliet developed a drug in 2001 for degeneration-based infertility. She tested this treatment on her sister Rachel Carlson who was infertile from cancer treatment, and her sister was able to successfully become pregnant. Her sister later carried the child through to a successful birth. Her work attracted the attention of the Others, who recruited Juliet and brought her to the island to solve their infertility problems. It is unknown whether Juliet was able to solve the former problem of degeneration in reproductive capacity, or whether it was truly a problem and not a flippant example by Alpert, but Juliet did work on ensuring that pregnant mothers survived their pregnancies. However, Juliet's proved unsuccessful, with the mothers always dying during pregnancy, including Sabine and Henrietta ("Not in Portland") ("One of Us") ("The Other Woman")
Juliet was unable to find a solution to the immune problem. She theorized that the problem occurred at conception and proposed to Ben a plan where she would take a subject off the island for conception to test the theory, but Ben rejected the idea of anyone leaving the island.
When Oceanic Flight 815 crashed on the island, however, Claire Littleton was 8 months pregnant. She provided the Others with the perfect control case, and having conceived off-island meant Juliet could test her theory about the immunity issue being related to something occurring at conception on the Island. Juliet has said that Ethan, who had infiltrated the mid-section passengers, took blood samples from Claire, but soon discovered that her results were consistent with other mothers who later died on the Island during their pregnancies (despite conceiving off-island). Juliet claimed Ethan began treating Claire and administering injections. These injections were said by Juliet to be her created drug. ("One of Us") Ethan was seen injecting Claire with a drug that had the same DHARMA Initiative label as the vaccine. ("Maternity Leave"). It seems unlikely, however, that the vaccine and Juliet's serum were one in the same as Desmond and other male staff members of the DHARMA Initiative were also given injections of the vaccine.
According to Juliet, when Ethan's identity was eventually discovered, he decided to kidnap Claire on his own initiative. Claire was kept at the Staff medical facility, where she was given more drug treatments, and her medical condition was closely observed ("One of Us")
Claire escaped from the Staff with the help of Alex. As she was leaving, the medical team of the Others was seen preparing for a surgical procedure probably involving Claire. Alex said that they intended to cut the baby our of her ("Maternity Leave"). Ethan pursued Claire and demanded that she be returned to him. He was captured in an attempt to kidnap Claire again and was afterward shot six times while lying unarmed on the ground by Charlie resulting in his death ("Homecoming"). Claire gave birth without complications to Aaron and after Ethan's death there were no further attempts to kidnap either Claire or the baby.
Claire at one point was concerned that Aaron was ill and obtained some of the vaccine that Desmond had taken every nine days at the Swan. It is unclear how much of the drug Claire gave Aaron or how long she continued to give it to her child.
It was later revealed that Claire has an "implant" under the control of the Others. The activation of the implant was able to induce what was said by Juliet to be a withdrawal symptom from no longer having injections of her serum, within 48 hours. However, this is obviously a lie as it was the Others who activated the implant to cause Claire to be symptomatic. Juliet administered an injection of the vaccine to Claire, but it is unclear if this had any effect in her recovery. ("One of Us")
Juliet then discovered that Sun was pregnant, and revealed that if she conceived off-island, there was a likelihood that the mother and child would both live (confirming Juliet's original theory). However, Sun discovers she became pregnant on the Island, causing Juliet to admit that without help, Sun will die before her third trimester. ("D.O.C.")
In fortuitous circumstances, however, Sun does manage to escape the Island, and is shown having a healthy baby in South Korea. ("Ji Yeon")
The following characters have been pregnant, or have taken pregnancy tests.
|Mother||Father||Positive Pregnancy||End Result|
|Ana Lucia Cortez||(Presumed) Danny*||||Unborn baby was killed by Jason McCormack|
|Beth*||her husband*||Died before giving birth|
|Cassidy Phillips*||James "Sawyer" Ford||Gave birth to Clementine Phillips|
|Kate Austen||Kevin Callis*||Pregnancy test was negative|
|Rachel Carlson*||Injection||Gave birth to Julian Carlson|
|Sarah Shephard*||Jack Shephard||Pregnancy test was negative|
|Sarah Shephard*||Unknown||Pregnancy starts sometime in late 2006/early 2007, as seen in April 2007 flash-forward|
|Susan Lloyd*||Michael Dawson||Gave birth to Walter Lloyd|
|Henrietta*||Unknown||Died from pregnancy|
|Sabine*||Unknown||Died from pregnancy|
|Claire Littleton||Thomas*||Gave birth to Aaron Littleton|
|Danielle Rousseau||Robert||Gave birth to Alex|
|Sun-Hwa Kwon||Jin-Soo Kwon||Gave birth to Ji Yeon Kwon off-Island|
|Emily Linus*||Roger Linus*||Died after giving birth to Ben|
|Emily Locke*||Anthony Cooper||Gave birth successfully to John Locke three months premature|
|Penelope Widmore||Desmond Hume||Gave birth successfully to Charlie|
|Amy||Horace Goodspeed||Gave birth successfully to Ethan, 2 weeks premature|
(*) Flashback character
Details are listed below, sorted by episode.