The 38 year old was arrested on Friday on suspicion of preventing a lawful burial and perverting the course of justice.
The Met said the child had not been seen in the 11 years since its disappearance was first reported.
A woman, 31, previously charged in connection with the investigation, appeared in court in July.
Victoria Gayle, 31, previously of West Hendon, north London, was charged after police discovered the remains of another baby at a home in West Hendon in June.
A post-mortem examination at Great Ormond Street Hospital was unable to determine the cause of the child's death.
Ms Gayle is due to appear in court again in later this month.
A 50-year-old woman and a 52-year-old man remain on bail.

Dentsu is accused of violating labour standards after Matsuri Takahashi, 24, killed herself in 2015.
Her friends said Ms Takahashi  - who had been at the firm for less than a year - claimed to be so busy she slept just 10 hours a week.
Death from overwork is relatively common in Japan, where it has its own word: karoshi.
Ms Takahashi is reported to have worked 100 hours of overtime a month for some time before her death.
She died on Christmas day 2015. According to reports, a note left behind for her mother included the line: "Why do things have to be so hard?"
The Asahi Shimbun newspaper said the company was being charged over illegal overtime, and that prosecutors were seeking a fine.
That would effectively end the investigation, Kyodo news agency reported.
The case against Dentsu targets the corporate entity, but not any individuals.
But Kyodo news agency quoted Ms Takahashi's mother as saying she was "unconvinced" about the lack of charges for her daughter's superiors.
The high-profile case has led to renewed calls for changes to Japan's notoriously long working hours and illegal unpaid overtime.
Officially, there are several hundred cases of karoshi each year, although campaigners say the real number is even higher.
Dentsu has made a number of reforms in the aftermath of Ms Takahashi's case, reported to include turning off the lights at 22:00 every night in a bid to force employees to leave.
The agency's chief executive, Tadashi Ishii, offered his resignation last December over the controversy.

The collision happened on the A21 Bangor to Newtownards dual carriageway, near the Green Road junction, at 19:40 GMT on Thursday.
A number of people were taken to hospital after the crash. The road was closed overnight but has now reopened.
Insp David McClements appealed for anyone who witnessed the collision to contact police.
Police investigating the disappearance of a baby born in north London in 2004 have arrested a man in Hertfordshire.
[NEXT_CONCEPT]
One of Japan's leading advertising agencies has been charged over the death of an employee from overwork.
[NEXT_CONCEPT]
A man and a woman have been critically injured in a three-car crash in County Down.