Lois and Hal have a pregnancy scare that results in an argument. While they’re fighting, Dewey gets worried and talks to Francis, Reese, and Malcolm.
Each conversation ending in a flashback to the birth of all of them.
The episode begins with Hal and the boys watching a Wile. E Coyote cartoon with Malcolm asking Hal if they can watch what Francis wants since he is returning to Marlin Academy the next day. Lois calls Hal to the bedroom and an argument arises over the possibility of Lois being pregnant again since she is two weeks late with her period.
Dewey listens to the argument and Francis wonders why he is taking so long to get him a drink. After being told about the argument, he tells his little brother not to worry and says that making him a sandwich will take his mind off of it. Hal and Lois look back at the memories of their children's births when they weren't ready for Francis being born while Hal and Lois got married, Hal questions that Lois didn't think it was a big deal before, but Lois changed her mind about marriage.
After Francis was born, they moved into an apartment complex that is a beautiful pure white. Hal accidentally leaves Francis inside a closet and after finding him, Lois says she'll never let him out of her sight again.
Back in the present, Francis knocks on the door but Lois tells him to go away.
Dewey asks Reese about their parents arguing, Reese assures him they'll be affectionate soon, claiming the arguing is merely an act. He then watches bugs fly into a bug zapper before touching it and getting zapped himself.
In another flashback, three years after that, Lois is pregnant with Reese and he kicked too hard while in the womb. The apartment isn't pure white anymore as Francis has colored on the walls and chairs and the upholstery on the couch has been replaced. Hal heads off to work, announcing he can't take anymore breaks and has to work 14 hours every day. Lois convinces him to talk to his boss and make a change, because Francis is destructive and Reese is pounding her from inside. Hal heads off after returning Francis who tried to get out. Hal asks to cut back on his hours and ends up working beside the bathrooms. He receives a call from Lois at the hospital. He tells her how he trained his boss and thought more of him. The doctor comes into the delivery room and says Lois is only two centimeters dilated, but Lois refuses and pushes harder in order to relieve herself of Reese. The doctor is amazed, but Reese kicks him in the nose immediately after being born, Hal states that they'll be fine.
After driving across town to get a pregnancy test, Lois and Hal continue to argue about which route he took. Since Francis is in the bathroom, they go to the backyard. Dewey peeks out of his room and asks Malcolm, who is doing his homework, if they're getting a divorce, Malcolm reassures him that everything will be fine, and then tells him to be quiet after pestering him too much. The next flashback occurs.
Two years after that, the family has moved out of the apartment and moves into their current house. Hal is attempting to educate Reese, but in turn, grants intelligence to the unborn Malcolm. Another argument arises, but Hal decides to go for a drive before he says something he'll regret since Reese is there. After leaving, Lois tells Reese that her and his father are just going through a tough time for the past few months. Suddenly her water breaks, and despite calling for Hal he has already driven off. Lois tells the two boys they are going to the hospital, which the 5 year old Francis objects to due to being tricked into getting a shot last time. Due to her being a liar, Francis gets in the car and locks his mother out. Hal comes back seeing an ambulance in the yard and runs up to a neighbor, who congratulates him after Lois gave birth on the front lawn. Hal asks his wife if she'll like some of his Slurpee, Lois tells him to leave her alone.
Back in the present day, in the backyard, Hal asks if Lois needs help, only for her to tell him to leave her alone again. Dewey looks on as the argument reaches its pique, shoving banana in his ears to avoid hearing a swear word.
The final flashback occurs 4 years after the previous one.
While in the womb, Dewey felt warm light of the cracked microwave. Reese is out of control, Malcolm is using a microscope at age 4 and only one socket in the kitchen works, forcing them to plug all their appliances close together, due to Lois getting chills and not being able to use an extension cord. The doorbell rings and Lois sees a friendly police officer with a 9 year old Francis in tow, telling her that Francis took a joyride on a street cleaner and he is given a summons for a juvenile court date, which by this point everyone involved was used to. After dragging him inside, Francis is chastised for his behavior and sent to his room. Lois blames Hal for regaling him with tales of his wild youth. Hal claims they are cautionary tales, but Lois doesn't agree. Reese then runs up to them with a ball shoved in his mouth, and Hal tries to get it out and yells at Lois to stop telling him how wrong he is. Malcolm comes into the kitchen announcing that he accidentally broke his chemistry set. Francis then comes out of the bedroom coughing from white gas coming out of the room. Malcolm states he tried to make invisible ink, but accidentally made chlorine gas, they all run out into the backyard right when it begins to rain. The boys run off to play, and Hal announces to Lois that the rain must be his fault as everything always is, she then says she's having the baby, but they can't go to the hospital. Lois tells Hal they have to find a way to fix their relationship without killing each other. Hal is then forced by Lois to tell her 7 reasons why he loves her. The couple then confesses how they love one another and each little thing they do, they both embrace and reconcile before Dewey is born.
Later, Dewey, who has been listening to his parents, is happy that they are not arguing anymore, now saying that they love each other. Lois is revealed not to be pregnant.
The boys get into a squabble inside and the parents look at their children and how they wouldn't give up a single one. Lois still wishes for a girl, Hal says there are 5 to 1 boys and she's still winning.
- A lot of information about the births of the boys are learned in this episode. Francis and Reese were the only two boys to be born in a hospital. Reese also kicked Lois a lot, while in her womb and caused a lot of pain when she was giving birth to him, and forced Reese to come out hours before he was intended to just to get it over with. When pregnant with Malcolm, Lois and Hal had to move out of the apartment they previously lived in and move into their current house. Malcolm was born on the front lawn because Hal was gone while Lois went into labor and Francis locked her out of the car. Dewey was born in the backyard because Malcolm had released a bunch of toxic fumes in the house and they couldn't get the keys to the car and drive to the hospital.
- Ever since Hal and Lois moved into their new house, all of their boys were born on the house property instead of the hospital. Malcolm and Dewey, as mentioned before, were born on the front and back lawn, respectively, and although it was not shown in this episode, Jamie would be born in Hal and Lois' bedroom in the episode Baby Part 2.
- It was revealed that the reason Malcolm became a genius is because while Lois was pregnant with him, Hal gave a bunch of musical learning activities to Reese about a bunch of random information. Reese completely ignored this, but Lois was present in the room most of those times, and Malcolm's brain absorbed the information, while he was still developing.
- Dewey felt warm waves from the microwave, while Lois was pregnant with him, which is what caused him to have his weird personality.
- Lois and Hal have a pregnancy scare and assume they're having a fifth child. Although it turns out to be false in this episode, they'd receive another scare in Grandma Sues, which turned out to be true.
- The song "Been Here Once Before" bye Eagle-Eye Cherry is featured throughout the episode.
- When the ball rolls in the gutter while the boys are playing catch you can see a part of the lighting setup on the left side.
- The actor who played Malcolm's 4 year old self has brown eyes, when Malcolm's primary character has blue eyes.
- When Francis locks Lois out of the car and says "You're a liar. You're a liar", the reflection of a camera man filming the scene is seen on the back window.
- The events of each boy's birth shows that Reese is 2 years older than Malcolm which contradicts the information given about their ages later in the show where it is said that Reese is one year older than Malcolm.